Although the film was set in the "Present Day", 1994 at its release, the subsequent TV shows provide an alternate dating system. Because the show is so well accepted as a canon continuation of the story, particularly by MGM (who own the rights to the franchise), the dating system described in the show is used in this article. Furthermore, most of the story of Stargate comes from the TV shows, and so they take precedence. The dating system of the show portrays events as taking place simultaneous, or at least in the same year as, the airdate of each episode. As the first episode aired on July 27, 1997, and the show begins one year after the events of the film, the film's "Present Day" is reinterpreted as 1996.
From indications in the show, each season of it is intended to correlate to one year in the show's story (and each season takes one year to air). For example, in Season 9, many characters mention how it's been "8 years" since they first came into conflict with the Goa'uld (beginning of Season 1). Using this information, it is possible to extract timelines based on information stated in episodes and also the relative positioning of the episodes throughout a season.
Unknown, but probably before 50 million years BC 
The Alterans (Ancients) evolve and progress to a scientific level far beyond that of present-day humanity.
An ideological split appears between two factions of the Alterans: One progresses towards an increased belief in religion, the other towards belief in science. The Alterans who believe in science come to the Milky Way and settle on Earth. They colonize many planets and seed a network of Stargates throughout the galaxy, the oldest of which, the Antarctic Stargate, was planted on Earth 50 million years ago.
Members of the Alterans in the Milky Way and in their home galaxy Ascend to a higher plane of existence.
The ascended Alterans within the Milky Way, who are known as the Ancients, and the ascended Alterans within their home galaxy, who are known as the Ori, continue their ideological war across both the Ascended and lower planes. As the ascended Ori continue to interact with the lower planes they translate their sense of divine right into a very literal stance, and attempt to convert all sentient beings to a religion that centers around worshiping them, called Origin. Meanwhile, the ascended Alterans within the Milky Way gravitate towards a belief of free will and self-determination for all life.
The Alterans settle within the Pegasus galaxy, colonizing several worlds and instigating the evolution of humanity on others. Their people come to be known as the Lanteans, or the Ancestors to the seeded humans.
The Lanteans seed a world home to the Iratus bug in the Pegasus Galaxy and the bug acquires human DNA, either through feeding on humans, or through the aforementioned genetic seeding. It rapidly evolves into a humanoid form, known as the Wraith.
After the Wraith develop their numbers and technology to a sufficient level, they enter into war with the Lanteans. The Lanteans, with their vastly superior technology, win almost every battle, but due to the superior numbers of the Wraith which are created through the use of cloning powered by stolen ZPMs, cannot win the war.
In their desperate search for better weapons against the Wraith, the Lanteans create an artificial life form known as the Asurans from nanite technology. However, the Asurans achieve sentience and throw off the yoke of their creators. The Lanteans attempt to destroy the Asurans, but fail.
In the Milky Way galaxy, the Goa'uld and Unas evolve on P3X-888. The "second evolution" of humanity evolves on Earth.
The Ascended within the Milky Way shield the galaxy from the Ori.
The Asgard in the Ida galaxy begin exploring space within and outside their galaxy (c. 30,000 BC).
The Goa'uld learn to take the Unas as hosts and to use the Stargate on their planet, which has been left there by the Alterans. They travel to other planets in these Unas hosts, conquering and multiplying.
Due to their absence from the Milky Way Galaxy, and the extreme age of the technology which remains, those species which evolve after their exodus name the Alterans 'the Ancients'.
The war between the Wraith and the Lanteans in the Pegasus galaxy escalates to the point where Atlantis is constantly under siege. The Lantean people decide to leave Atlantis for Earth by going through the Stargate. Atlantis, protected by a powerful force-shield, is sunk to the bottom of the ocean. The Lanteans leave Atlantis to find that the native peoples on Earth are quite primitive, preventing them from ever rebuilding their great civilization; the Lanteans then live out the rest of their lives with the native peoples.
The Ancients on Earth go on to influence the language and mythology of Ancient Rome and the myths of Greece; their research on Ascension forms the basis of Buddhism. Many Ancients continue to use the Stargate network, and form an Alliance of Four Great Races, with the Nox, the Asgard and the Furlings, who have become very advanced. This Alliance lasts for centuries.
The Goa'uld discover Earth and Humans, and abandon Unas as hosts. They take dominion over many areas of Earth, particularly Egypt, and pose as Gods.
Alternate timeline:Elizabeth Weir is rescued from the ocean of Atlantis after accidentally travelling backwards in time from the year 2004, using an altered time-travel capable Puddle Jumper. She befriends the Ancient Janus, who programs Atlantis to rise from the ocean if the shields fail, blocks all but the Earth gate from making connections to Atlantis, and makes alterations so that instead of using the multiple remaining ZPMs in parallel, Atlantis uses the remaining ZPMs sequentially, and puts Weir in a cryonic sleep, to be automatically awoken when an active ZPM becomes drained so that she can exchange them; and to be found by her alternate self 10,000 years later.
The alternate timeline, although explained after the first, is in fact the real one correlating to the main reality of Stargate.
Between 8,000 BC and 3,000 BC
Humans become slaves and worship the Goa'uld. In Egypt, the theocracy founds Egyptian mythology.
Various Goa'uld transport humans as slaves to other planets using the Stargates in order to increase their numbers. (This results in the Goa'uld affecting various other Earth mythologies.) In particular, ancient Egyptians are taken to the planet Abydos to work as slaves.
Ra becomes the Supreme System Lord and the only Goa'uld ruling Earth.
The last remaining Ancients either die out or Ascend.
The Sodan, a faction of Jaffa, rebel against the System Lord Ishkur and free themselves. They start on a journey to find Kheb before settling on a hidden Ancient planet.
Omoroca arrives on Earth and attempts to prevent the Goa'uld from securing domination over Humanity. The Goa'uld Belus kills Omoroca, though it has been theorized that her influence led to the eventual Human rebellion.
The Humans of Earth rebel against the Goa'uld Ra, possibly instigated by the Oannes, and free themselves of his domination. The Stargate on Earth is buried and Human civilization begins its natural evolution.
SG-1 arrives in ancient Egypt via a time-traveling Puddle Jumper. They locate a ZPM that belongs to the ruling Goa'uld, Ra, and bury it. However, their actions upset causality severely.
SG-1 instigates an uprising against Ra, not wanting to live in servitude and hiding. The uprising is successful, causing Ra to leave Earth with the Stargate.
The future SG-1 came from has been drastically altered, primarily because Ra took the Stargate with him when he departed. Prepared for just such a possibility, SG-1 has left a message for the future; an alternate SG-1 minus their Daniel Jackson comes back to Egypt and helps the original Daniel Jackson fix the timeline. They instigate the rebellion again, and it is again successful, but this time Ra leaves without the Stargate, which is sealed in the sands of Giza. Ra goes to Abydos.
The second half of this alternate timeline (the "fixed" half) is in fact the version of the timeline corresponding to the reality of the Stargate universe after Season 8 of Stargate SG-1 (Season 1 of Stargate Atlantis).
The Ancient Moros, later known as Merlin, de-Ascends on earth, where he begins building a weapon to neutralize Ascended beings, the Sangraal. He befriends a group of knights and creates the basis for the Arthurian legends. An Ascended ancient, Morgan Le Fay, destroys the weapon but places Merlin in stasis, so that he may re-build it if the Ori ever threaten the Milky Way.
Researchers manage to activate the Stargate, and Dr. Ernest Littlefield, fiancé of Catherine Langford, travels through. He is not able to return until 52 years later, when he is discovered and rescued by SG-1. The military canceled the experiments after his disappearance. Some time after this the Stargate is moved to an armory and locked away.
Daniel was 8 years old in 1973 when he witnessed the deaths of his parents. He is asked his birthdate after being hurt in the Season 3 episode "Forever in a Day".; his birthplace is listed on his personnel file, briefly shown in the Season 6 episode "Disclosure".
In the Season 4 episode "Entity" Sam's date of birth appears on her personnel file whilst an AI searches the SGC's records.
In the Atlantis Season 4 episode "Quarantine" Rodney's year of birth is discussed whilst Sheppard recalls Rodney's password.
SG-1 arrive in 1969 after being sent back in time from March 1999, by a freak accident involving a Stargate's wormhole passing through a solar flare. They meet a young George Hammond, who helps them get back to the future. Teal'c also learns to drive.
In the Season 9 episode "Collateral Damage" he says he was about 10 years old in 1981 and remembers the launch of the first shuttle, the Columbia. And in the Season 10 episode "200", Lt.Col. Carter and Doctor Jackson tell him that they went back in time to 1969, a year before he was born and joke that Major General O'Neill is actually his dad.
Archaeologists Claire and Melbourn Jackson are crushed by an Egyptian coverstone while it is being moved in a museum. This is witnessed by their eight-year-old son, Daniel Jackson, and remains one of the most powerful and traumatic moments in his life.
In the original film, Jack's son was named Tyler — his name visible on a plaque in his room. Fans have speculated that one of these two names is in fact the middle name (i.e. Charlie Tyler O'Neill or Tyler Charlie O'Neill)
Daniel Jackson, now a brilliant Egyptologist and linguist, but shunned from the academic world due to his farfetched theories about the construction of the pyramids, gives a lecture on such a theory. As it fails, Catherine Langford contacts him and takes him to Cheyenne Mountain to aid in the deciphering of strange hieroglyphs that were found on the cover-stones of the still-enigmatic Stargate.
Jackson realises they are not hieroglyphs but constellations, such that seven can plot a course through space. The Stargate is revealed to him, and he figures out the seventh symbol to complete a dialing address to the planet Abydos. Jack O'Neil commands a team, with Jackson as interpreter, and they step through the gate. O'Neil is given a secret order to detonate a large nuclear bomb on the other side if there is any threat.
On the other side they discover the descendants of Ra's slaves, the Abydonian people. Daniel is married to a native, Shau'ri, as a gift, although he doesn't realise what happened until later.
When Ra realises they have come he attacks and captures the members of the Earth exploration team that remained with the Stargate. There is a further problem — the cover stones on this side are broken and Jackson can't find the seventh symbol needed to dial home. O'Neil tries to detonate his bomb but finds it has been taken by the Goa'uld; Ra's guards capture O'Neil and Jackson.
Native Abydonians, including Skaara, help Daniel and O'Neil escape. When Daniel works out the seventh symbol, they hatch a plan to reach the gate before Ra uses it to send O'Neil's nuclear bomb back to Earth, enriched with the mineral that is mined on the planet — the result would be apocalyptic. Ultimately, after they have overpowered Ra's guards, Ra tries to escape in his ship, but O'Neil Rings the bomb onto his ship, where it detonates in space and kills Ra, freeing the Abydonian people.
Daniel Jackson helps O'Neil dial home, but stays on Abydos after having fallen in love with his wife Shau'ri.
O'Neil returns to Earth and files a false report that Daniel Jackson was killed and that the Abydonian gate was destroyed. He finally retires.
Apophis, Ra's enemy and also a Goa'uld System Lord, is looking for potential hosts for his Queen, Amonet. He sends a small attack force through the gate, killing a few guards at Cheyenne Mountain and taking a female guard back through the gate.
George Hammond, the present commander of Cheyenne Mountain, calls in Jack O'Neill, who is forced to admit the truth about the Abydos stargate. Samantha Carter joins the base, and forms a part of O'Neill's team.
O'Neill returns to Abydos and relocates Daniel Jackson. They find a catacomb engraved with thousands of gate addresses, realising that there are more than two gates — that there is, in fact, a huge network.
Apophis captures Skaara and Daniel's wife, Sha're (formerly spelled Sha'uri in the film). Daniel leaves the Abydonians to search for her and bring her back.
They are captured on Chulak and will soon be executed; however, Apophis' First Prime, Teal'c defects to their cause and helps them escape.
Sha're is taken host by Amonet and Skaara by Apophis' son, Klorel.
On returning to Earth, the base is dubbed Stargate Command, and SG teams are created to use the gate to find technology and allies to fight the new threat of the Goa'uld. Daniel Jackson decides to join the SGC's quest, so that he can find and save his wife and his brother-in-law Skaara.
The Iris protecting the base against unauthorized inbound travelers is installed.
Daniel Jackson, Teal'c, Samantha Carter and Jack O'Neill become official members of the primary SG team — SG-1.
SG-1 do not realize these races' importance until much later.
Daniel Jackson realises that Ernest Littlefield went through the gate in 1945 and never returned. SG-1 go on a mission to rescue him with Catherine Langford. He is brought back home and reunited with her, but whilst they were there Daniel Jackson learns about the Four Great Races.
The actual discovery of the Ancients would come later; this gate and DHD are utilized by the NID for a while before being secured. However, the DHD would soon lose all power, as it is one of the oldest (believed to be the oldest) in the entire Stargate network.
SG-1 disobey orders and use the Stargate to travel to one of the two Ha'tak attack vessels that Apophis is attacking in. Skaara/Klorel is in control of it. They fill the ship with tactical C4, and although they are not able to save Skaara, they avert the attack, and both Apophis and Skaara get away.
Daniel Jackson returns to Abydos, fulfilling a promise that he would return in one year. There, he discovers that Sha're has been returned by Apophis, as she is pregnant and he wants her safe from his enemies; one effect of the pregnancy is that Amonet is subdued and not in complete control. For the moment, Daniel Jackson is reunited with his wife; he later delivers the baby. Once this happens, Amonet regains control but is incapacitated by Teal'c, who is dressed a Horus Guard (the guardians of the family of Ra). She later returns to Apophis, and tells him that a rival Goa'uld System Lord, Heru-ur, took the child, having recognised Teal'c's armour. The child is given to Sha're's father, and they go into hiding.
Jack encounters a Repository of the Ancients and has Ancient knowledge downloaded into his brain, leading to him creating a power-source capable of allowing the Stargate to dial 8 chevrons and connect to the Asgard home galaxy. He befriends the Asgard in person, and they realign his mind before sending him back.
Apophis is defeated by another powerful Goa'uld, Sokar. He crash-lands, and when SG-1 find him, he is so badly wounded he asks for sanctuary on Earth; SG-1 reluctantly grants it to him. When Sokar finds out that the Tau'ri are holding Apophis, he begins to attack Earth; he will stop on the condition that Apophis is handed over to him. Apophis dies, and the SGC hands his body over to Sokar.
Sokar later uses a Sarcophagus to revive Apophis and torture him indefinitely.
Hathor captures and tricks SG-1. She makes each of them believe that they have woken up alone at the SGC, 79 years in the future. SG-1 quickly figure out what's going on, and Jack kills Hathor. With the help of several SG teams, the Tok'ra and Jaffa, they defeat Hathor's army and escape home.
With the help of the Asgard, SG-1 negotiate with the System Lords to bring them into the Protected Planets Treaty. Although the negotiations are successful in preventing the Goa'uld from attacking Earth, the treaty does not protect SG teams on other planets.
Daniel Jackson finds Sha're, still possessed by Amonet. Amonet captures him and tries to kill him. Teal'c steps in at the last minute, and is forced to kill Sha're to stop Amonet. In the last moments of her life, Sha're manages to transfer a message to her husband that he experiences in a set of visions. She tells him where her son, the Harcesis, is; Daniel can and must now find this boy, who has the knowledge and power to defeat the Goa'uld.
While trying to rescue the Tok'ra Jacob Carter, SG-1 is captured by Sokar on his prison world, but manage to escape. One of Sokar's underlings reveals himself to be Apophis; who kills Sokar and takes control of his armies.
Klorel, Apophis' son in the body of Skaara, crash-lands on Tollana. A trial (called triad) is held to determine as to who has the right to possess the body, with Daniel and Jack defending Skaara. It is decided in Skaara's favour. Skaara is finally freed of Klorel, and is infinitely grateful to Daniel and Jack; he returns to his homeland Abydos. After the trial, the Goa'uld disable every Ion Cannon at once so their ships can destroy Tollana; however, Teal'c and Lya of the Nox save one by cloaking it, and use it to destroy the Goa'uld attack force.
Daniel Jackson figures out where the Harcesis is: a planet called Kheb. There, SG-1 encounter a Zen monk who is teaching Ascension, which Daniel thinks may be the basis for Buddhism on earth. Daniel learns much about Ascension, and eventually finds the child, who is being guarded by the Ascended Ancient Oma Desala. Tempted to take his son back with him, Daniel realizes that the child is safer with her and leaves him in Oma's care.
The Asgard enlist Jack O'Neill's help to defend them from their nemesis, an enemy worse than the Goa'uld: the Replicators. Thor's ship is infested with them and heading for Earth, meaning disaster if it arrives. SG-1 manage to cause the ship to crash-land in the ocean, where the original Stargate is lost; the SGC replaces it with the second Gate found in "Solitudes". Despite this seeming victory, a single Replicator survives and crawls aboard a submarine; it soon replicates into a small army that is defeated when the submarine is destroyed.
Sam goes to the Asgard homeworld at the same time to defend them from Replicator attack. She hatches a plan of using the new Asgard flagship designed to fight the Replicators to lure them into hyperspace and then detonate the bait ship. The Asgard hesitate due to the resources put into the ship but agree. It works, and the Asgard are in Earth's debt.
Season 3 finale and Season 4 premiere; First appearance of the Replicators.
The SGC finds itself unable to open the Stargate because the Russian Gate is being held open indefinitely. The Russians did not have a Gate originally, but recovered the Gate left in the ocean after Thor's ship crashed and hooked it up to its original DHD from Giza, recovered after World War II from the Nazis. Their Gate is now the primary Gate for Earth because of the DHD, which takes priority in the Stargate network when both units are powered. The Russians have been conducting a secret Stargate program with the help of rogue NID agent Col. Maybourne, and by only turning their gate on when needed, keep the American SGC oblivious. However, they have encountered a glitch and cannot turn their Gate off. The Russians enlist the help of SG-1 to deactivate their Gate and combat the alien force that has taken control of their compound. Afterwards, they agree not to conduct their own Stargate program in exchange for a share in the alien technology that the SGC acquires and their own team within the SGC.
The Harsesis has grown abnormally quickly, and contacts the SGC. His name is Shifu. Jackson wants Shifu to give him the knowledge of the Goa'uld so that they can defeat them. However Shifu teaches Daniel that the knowledge is so evil and powerful that it will corrupt any who know it; Daniel realises that he cannot simply be just "told" what to do. Shifu Ascends.
Apophis' whole fleet attacks a Tok'ra base, so Jacob calls in SG-1. He and Sam hatch a plot to use a Stargate to blow up a nearby sun — engulfing Apophis' fleet. They are successful, but Apophis' ship escapes, and he brainwashes Teal'c to be loyal to him again. However, Replicators overrun Apophis' ship, which is en route to his home planet, causing him to eventually crash into that planet, marking the final death of Apophis. Teal'c's master Bra'tac helps him return to sanity.
SG-1 receive a note sent back in time from their future selves in an alternate timeline, warning them never to travel to P4C-970. They travel to a nearby planet and meet the Aschen. Daniel figures out why the note was sent back at the last minute — the Aschen have a secret plan to induce mass sterility in humans, allowing them to take over Earth. SG-1 escape and cease contact with the Aschen.
Teal'c becomes trapped in the Stargate's buffer, and any incoming or outgoing wormhole will result in him being lost forever. The Pentagon has given a deadline of 48 hours at which point normal Stargate operations will resume. Dr. Rodney McKay is first introduced, sent as the foremost Stargate expert to help Carter figure out how to get Teal'c back. The SGC needs a DHD to establish an event horizon without establishing a wormhole to get him out. Daniel Jackson, along with Major Davis, go to Russia and negotiate for the use of the Russian DHD. Eventually, the Russians agree and Teal'c is saved, unaware of the entire ordeal. Unfortunately, the DHD is hopelessly ruined in the process.
The System Lords gather to discuss the return of Anubis, who committed evils so great that not even the Goa'uld speak of them. Daniel Jackson manages to infiltrate this gathering and hear the discourse.
On the planet Langara, Daniel Jackson is exposed to lethal radiation poisoning to save the lives of millions when a nuclear experiment is about to go off. A Kelownan, Jonas Quinn, accompanies them back to Earth as he betrayed his government for SG-1's sake. As Daniel dies, he is visited by Oma Desala, who offers him the path of Ascension, so that he can continue to do good. Daniel accepts. He appears to Jack in a vision, and asks him to tell the doctors to let him die. In a final farewell, Jackson's Ascended form leaves the SGC through the Stargate.
First appearance of Jonas Quinn, last of Daniel for the season.
The awakening System Lord is revealed as Anubis, who on account of possessing technology vastly greater than the other System Lords, assumes effective control of the galaxy; his only opponent being Lord Yu. He attempts to attack Earth using an Ancient weapon that will cause the Earth gate to explode, but Jonas Quinn gives the SGC the idea of how to prevent annihilation; they send the Stargate into hyperspace, and replace it with the original gate which was salvaged by the Russians ("Watergate").
Jonas Quinn becomes part of SG-1, replacing Daniel Jackson.
SG-1 find and thaw Aiyana, who demonstrates her abilities as an Ancient, but dies of the Ancient plague.
Earth constructs its first interstellar cruiser, the Prometheus.
The replicators have developed the ability to generate human-form versions of themselves. One of these, Fifth, is more human than the others, being constructed with emotion. SG-1 help the Asgard trap the Replicators on a distant planet with the use of a time dilation device, exploiting Fifth's weakness; Sam feels guilty about this.
The USA (and SGC) hold a meeting to reveal the existence of the Stargate to the remainder of Earth's five major superpowers: China, France, and Great Britain. (Russia of course already knew and supports the SGC) They give them all information pertaining to what's been going on the past six years. (Canada is informed shortly after at an unknown time)
Anubis is searching for the Eye of Ra, a key (along with five others) to using a super weapon; and it is located on Abydos. SG-1 return to Abydos. There, Daniel Jackson appears in his Ascended form, and although it is against the rules, he will interfere and not allow Anubis to harm the Abydonians. Whilst searching for the Eye of Ra, Daniel discovers a tablet written by the Ancients pointing them to a Lost City of theirs — Atlantis. He realises that Atlantis is more important than the Eye of Ra — if SG-1 can find Atlantis then they will have access to the most advanced of all Ancient technology — enough to defeat the Goa'uld. Ultimately, just as the Eye of Ra reaches Anubis, who powers his weapons to destroy all of Abydos, a large portion of the combined fleet of all the System Lords led by Lord Yu (who managed to create an alliance of all the system lords against Anubis) surrounds Anubis. A battle follows, in which the system lord's fleet is destroyed. Anubis turns his weapons on Abydos. When Jackson tries to stop him, he is stopped and taken away by an unseen force — the other Ascended beings intervened — they would not allow him to interfere in mortal affairs. Anubis destroys Abydos, however Oma Desala Ascends the entirety of its population beforehand, Skaara included.
Jackson is found de-Ascended on an alien planet. He is slowly reintegrated into SG-1, as his memories have been wiped. A five-man SG-1 infiltrates Anubis' mothership, prevents it from attacking Langara, Jonas' homeworld, and destroys his planet-destroying superweapon. Ultimately, Jonas returns to Kelowna, and Jackson rejoins SG-1.
As the collective forces of all the system lords are at war with him, Anubis has developed an army of supersoldier drones, Kull Warriors, which are almost impossible to defeat. This gives him an even bigger advantage over the other System Lords.
Jackson is working on the Ancient tablet, trying to find the Lost City. Osiris (who was sent by Anubis) visits him in his dreams to try to locate the Lost City through him. SG-1 capture Osiris, and relieve her host of her burden. Jackson is getting close to figuring out the Lost City's location. Sam Carter and Pete hit it off in this episode.
Henry Hayes is inaugurated as President of the United States, and briefed about the Stargate program. (This marks one of the Stargate SG-1 anachronisms: US Presidents are always elected in even years and inaugurated in odd years. The US Presidential election, which Hayes won, should have been held at the end of 2004, and Hayes inaugurated in early 2005. The only solution to this problem is to assume that either the Stargate "alternate" reality has US Presidents elected a year earlier, or that the entire timeline should be shifted a year ahead)
SG-1 finds a Repository of the Ancients and, on impulse, Jack O'Neill has the Ancient knowledge transferred to his mind again. Jack uses the knowledge to take SG-1 to an offworld Ancient Outpost where they find an Ancient power source (Later identified as a ZPM).
The assault force of Anubis is destroyed when Jack uses the newly found ZPM to activate the weaponry in a hidden Ancient outpost beneath the ice of Antarctica.
Jack O'Neill places himself in cryogenic sleep to halt the decay of his brain, which is failing under the strain of the Ancient knowledge. The remainder of SG-1, who had previously thought the outpost to be the lost city of Atlantis, realize that the structure is too small, and that the city must be found.
Lieutenant Colonel Cameron Mitchell suffers injury defending SG-1's efforts while piloting his F-302 against the forces of Anubis.
Season 7 finale, (Mitchell's actions are not established until a Season 9 flashback.)
Teal'c begins to grow his hair.
After Anubis' defeat, Ba'al assumes control of his forces and begins attacks on the System Lords. The System Lords send a delegation to Earth to negotiate a treaty. The Goa'uld Camulus, with his forces being defeated, requests asylum and stays on Earth
The replicators escape from the time dilation device created by the Asgards. Thor uses the knowledge of the Ancients in O'Neill's brain to create a weapon to destroy the replicators. He then removes the Ancient knowledge. Thor uses the weapon to destroy the replicators on Orilla but Fifth and his ship escape. While on Orilla, Fifth creates a human-form replicator in the form of Samantha Carter.
Dr. Weir leaves the SGC to supervise research at the Antarctic outpost. Daniel discovers the 8 chevron address of Atlantis. O'Neill is promoted to Brigadier General and takes over as SGC commander. SG-1 remains a 3-man team. Dr. Weir leads an expedition team composed of members from many nations of Earth to Atlantis.
Arriving at Atlantis, the expedition team discover that the city is submerged and protected by a rapidly depleting shield. Luckily the city automatically rises with the impending failure of the shield.
The expedition team accidentally awaken thousands of hibernating Wraith.
Anubis, surviving the destruction of his fleet, travels to Earth, then to the SGC in Russian officers. It appears he can only interact with our universe using hosts or with his energy shield. However, the human host's body cannot handle the possession for long, and starts developing infections. Anubis makes it to the gate room, and leaves earth in the Russian officer. However, Sam Carter changed the dialing sequence to send Anubis to an ice planet.
Alternate timeline: The shield protecting Atlantis fails shortly after the arrival of the Atlantis expedition. The city does not rise from the ocean, and all expedition members except Elizabeth Weir die. Dr. Weir accidentally time travels to 8,000 BC.
A serum is discovered which not only protects a treated human from Wraith attacks, but also (when tested on Steve) poisons the Wraith who attacks a treated human. However, the serum turns out to have a 50% mortality rate.
The expedition team meet the Genii, and with their help discover the location of over 60 hive ships. However, relations with the Genii soon deteriorate.
The Human-Form Replicator of Sam Carter makes contact with Earth, claiming Fifth has overcome the Asgard/Ancient Weapon, and wants to help the SGC destroy him. However, during the tests at the Alpha Site, "RepliCarter" turns out to be using both the SGC and Fifth, who never really learned how to overcome the weapon. She destroys Fifth's ship, learns how to counteract the weapon, and escapes.
During a rescue mission to Atlantis, Prometheus is hijacked while answering a distress call. The crew, excluding Daniel Jackson, is transported to a damaged Al'kesh, by what appears to be a Kull Warrior. Daniel discovers that the hijacker is former Goa'uld host named Vala, who plans to sell the ship. Daniel and the crew are able to retake the ship, but Vala escapes.
The SG-1 Team find an Ancient ship (a Puddle Jumper) with Time Travel capability on a remote planet, ruled by former NID operative Harry Maybourne. SG-1 uses the ship's drone weapons to destroy a Goa'uld Ha'tak.
SG-1 find out that Ba'al is being overrun by the replicators. Teal'c and Bra'tac decide to take advantage of Ba'al's distraction and plan an attack on the Temple of Dakara, a symbol of Jaffa slavery under the Goa'uld, deep within Ba'al's territory.
Anubis contacts Ba'al, who in turn contacts the SGC, to warn that there is an ancient weapon in the Temple of Dakara capable of destroying all life in the galaxy. He requests Earth's help in destroying it before Anubis can use it.
Sel'mak realises that the weapon can be modified to only destroy replicators, and with the help of Ba'al, they can open all the stargates simultaneously to send the blast wave to every planet in the galaxy with a working stargate.
The weapon destroys all the replicators in the galaxy including the ones comprising the ship Daniel is held captive on.
Ba'al flees, revealing his weakness. The majority of the Jaffa join the rebellion, all but ending the reign of the system lords.
The SGC sends reinforcements to Atlantis using Ra's ZPM to power the stargate. They then send the Daedalus, SGC's newest 304, to Atlantis. Powered by the ZPM, the ship makes the trip faster than normal.
With the ZPM and the Daedalus, Atlantis is able to fight off a Wraith attack. Surviving Wraiths are led to believe Atlantis has been destroyed.
Aiden Ford loses his sanity from a Wraith enzyme. He goes AWOL from Atlantis.
Jack O'Neill leaves the SGC to head the Department of Homeworld Security. Major GeneralHank Landry becomes the new head of the SGC.
Lieutenant Colonel Cameron Mitchell takes command of SG-1 after his heroic actions during the Antarctic battle against Anubis' forces. His desire to lead the team of Carter, Jackson, and Teal'c is hampered by their desires to pursue other interests. However, he is successful in keeping Daniel Jackson and Teal'c on the team. Samantha Carter's assignment is at Area 51 as a researcher.
Vala Mal Doran returns with information that not only links the Ancients to Arthurian Legend, but also leads SG-1 to a cache of Ancient treasure and artifacts.
Using the ancient artifacts, Daniel and Vala make contact with a remote galaxy whose inhabitants are forced to worship the Ori. This contact alerts the Ori to the presence of humans in the Milky Way.
SG-1 Season 9 premiere, Atlantis Season 2 premiere. First mention of the Ancients former name, the Alterans. First appearance of the Ori.
The Ori make their first attempt to create a Supergate in the Milky Way. Such a gate would allow their ships to invade the galaxy. The location of the site is the Jaffa inhabited world of Kallana. They are unsuccessful, but Kallana is destroyed in the process, turned into a black hole.
The Atlantis expedition discovers the remnants of the Ancient experiment Project Arcturus. They attempt to complete the experiment, and end up destroying 5/6ths of the Doranda star system.
Stargate Command learns that Ba'al has been living on Earth and experimenting with cloning technology. He has created many copies of himself.
Dr. Beckett attempts to turn a Wraith named Ellia into a human with a new retrovirus he has been developing. The attempt fails, turning Ellia into something more like the Iratus bug, not less. Ellia is eventually killed but not before infecting Lt. Col. John Sheppard with the retrovirus.
A combined fleet of Tau'ri, Jaffa, Asgard, Tok'ra and Lucian Alliance ships travel to the planet designated P3Y-229 to intercept and stop an Ori fleet from arriving through a newly discovered Supergate. Four Ori ships emerge from the Supergate the battle results in a complete loss with almost all of the attacking ships destroyed including the Korolov, Earth's newest 304 under the control of the Russians. The Odyssey escapes from the battle.
A weakness in battling Ori ship shields is found, allowing ring transport onto the ships.
One of two Wraith hive ships headed for Earth is destroyed and the other, with a crew mutated into humans through the Wraith retrovirus, is captured. The Orion is destroyed in the firefight.
The Wraith retrovirus proves extremely potent against all Wraith onboard the hive ship except for the Queen. The human form Wraith are taken to a nearby planet, and their ship is seized by Atlantis personnel.
When the Wraith on the planet manage to send a signal to their brethren, the Hive Ship that is under Atlantis's control is destroyed after presumably killing all the Wraith on the planet.
Richard Woolsey goes to Atlantis to evaluate Dr. Weir's leadership of Atlantis via Asgard ship.
SG1 goes to Atlantis to connect the supergate to a Pegasus Galaxy spacegate. A Wraith Hive Ship and an Ori ship are destroyed in the process.
The entire Atlantis expedition except Lt.Col. Sheppard fall under the influence of a person named Lucius Lavin.
SG-1 Season 10 Premiere, Atlantis Season 3 Premiere.
Ba'al resurfaces and has the SGC get his clones because they want to kill him. They escape and turn Stargate Command into a battlefield. The Ba'als escape with the list of addresses in the SGC's Ancient database.
The Jaffa attack a world converted by the Ori with the Dakara Superweapon, wiping out all life on the targeted planet, with the sole exception of Adria. A team of Jaffa warriors is sent to seize the Ori warship that has landed on the planet. SG-1 also investigates the ship, and comes into conflict with the Jaffa team.
Adria easily defeats the Jaffa warriors and mentally controls the Ori ship, setting it on a course to Dakara. She reveals that she will not rest until she has personally converted her mother Vala to Origin, and that the Ori have special plans for Daniel Jackson. Upon arriving at Dakara, Adria destroys the Superweapon, which she believes to be the only threat to Ori domination of the Milky Way.
Atlantis depletes the power of its ZPM during an experiment intended to create a superior power source.
The Lucian Alliance captures the Odyssey in a trap. Col. Emerson is killed by Solek. The Odyssey later escapes the Lucian Alliance when Mitchell fools Tenat into attacking Netan's Ha'tak. Tenat's last words are, "Damn you Cam Mitchell!"
SG-1 finds the planet where the Sangreal (Merlin's weapon to destroy the Ori) is located, but is forced to team up with both Ba'al and Adria to overcome the challenges set by Morgan le Fay. Deep within a cave, they are confronted by a dragon, and after it is overcome, SG-1 and Ba'al are transported to a chamber on another planet containing Merlin's frozen body and a means of building the Sangreal.
The team convinces Merlin to begin building a new Sangreal after learning that Morgan le Fay destroyed the previous one but due to the long period of time he spent in stasis, Merlin dies, but not before his mind is transferred into Daniel's. Daniel continues to build the Sangreal and learns that he now possesses Ancient powers.
Adria finds SG-1 and Ba'al, beaming into the chamber where Daniel is building the Sangreal while her army pours through the Stargate and engages SG-1. After Ba'al is struck by enemy fire, Daniel uses his powers to summon lightning strikes which kill the Ori soldiers. As Adria is about to kill SG-1, Daniel uses his powers to engage her, telling the team to retreat through the Stargate to Earth. Once SG-1 has left, Daniel is defeated by Adria and is taken to one of her ships along with the half finished Sangreal and the devices needed to finish the Sangreal.
The McKay-Carter Intergalactic Gate Bridge, a chain of 34 Stargates, 17 from Pegasus and 17 from the Milky Way, is established to allow rapid transport between Earth and Atlantis, without the need for a ZPM. Transit time is estimated at 30 minutes.
A group of Ancients from the battleship Tria retake possession of Atlantis, forcing the human expedition to return to Earth. Richard Woolsey and General O'Neill are allowed to remain as observers. When an Asuran ship attacks the city, they manage to send out a distress call to the SGC. Sheppard, McKay, Dr. Beckett, and Dr. Weir steal a Puddle Jumper and several anti-Replicator weapons for an unauthorized rescue mission, recruiting Teyla and Ronon to assist them before gating to Atlantis. They destroy the Asurans by modifying the shield to be a giant Disruptor Ray. It is also revealed Atlantis has underwater jumper bays.
The Daedalus establishes recon data that indicates the Asurans, Pegasus Galaxy Replicators, are constructing a fleet to attack the Milky Way Galaxy.
The new Daedalus Class battleship, Apollo, is dispatched to Atlantis. Using its nuclear arsenal, it commits a First Strike on the Pegasus Replicator's new fleet. The attack is successful, taking out all Primary and most Secondary targets.
The Asurans respond by bombarding Atlantis with a perpetual Laser-attack focused through an orbital Stargate, sent via Hyperspace.
Unable to sustain the Replicator attack indefinitely, the City is sunk to attempt to dissipate the beam. After failure, it is decided to abandon the planet, via the use of the City Stardrive.
Drained of nearly all operational power, Atlantis drops from Hyperspace prematurely from its intended new destination. It becomes adrift in deep space.
Replicators declare war on the Wraith after McKay changes their base code.
Atlantis expedition destroys Asura with combined help from Wraith and the Travelers
Athosians disappear without a trace.
Wraith attack and take control of the Midway station and several reach Earth but are eventually stopped by Teal'c and Ronon Dex.
Michael is found to have converted some of the Athosians into Human-Wraith hybrids and has released a modified serum (A modified version of the Hoffan Drug) into the humans of the Pegasus Galaxy as an attempt to attack the Wraith food supply.
Alternate timeline: The Phoenix, a new Daedalus class battlecruiser, is rushed into service under the command of Colonel Carter. The ship becomes ambushed by Micheal's fleet. The crew are beamed down to a planet while Carter tries to ram the ship into one of the Hives after the it suffers heavy damage. The hyperdrive overloads, destroying the Phoenix, three Hive-Ships and killing Carter.
Alternate timeline: After encountering the apparently benign and advanced human race the Aschen, Earth has defeated the Goa'uld and become a paradise. However, the Aschen have been slowly making humans sterile, thus taking over the planet passively. When SG-1 realize this they send a message back in time to warn their former selves never to travel to a certain planet.
SG-1, after having been trapped on a spaceship for 50 years are sent back in time; however Teal'c is within a time bubble so he retains the 50 years of time. Note: The "50 years" are subjective. Time was sped up for the crew, the universe only experienced a period of seconds. Teal'c is the only constant for that timeline.
Alternate timeline: Upon attempting to return to Atlantis, Sheppard is sent 48,000 years into the future due to a solar flare. He is eventually sent back in time with the help of a Rodney hologram so that he can change the events after he was lost