Buri, the first king of Asgard, is born.
Bor Burison is born to Buri, king of Asgard.
Odin Borson is born to Bor Burison, becoming the heir to the throne of Asgard. In 3460 BC, Odin defeats Surtur in battle. The Fire Demon would then spend nearly 5500 years recovering in Muspelheim, before his encounter with Odin's son, Thor, in 2017.
2988 BC (Convergence)
Convergence, or the alignment of the Nine Realms of Yggdrasil, occurs. This happens once every 5,000 years. During the Convergence, Malekith, genocidal leader of the Dark Elves, gains possession of the Aether (Reality Infinity Stone), and tries to destroy the Nine Realms with it. The Asgardian army, led by Odin’s father Bor, defeat Malekith and secure the Aether, hiding it away.
In an effort to save his race, Malekith kills most of his army and much of Bor's army, then puts his remaining forces into a sleep which lasts for millennia. Bor orders for the Aether to be hidden in the deepest area possible, where no one can access it.
Hela Odinsdottir is born to Odin Borson, becoming the rightful heir to the throne of Asgard as his firstborn. In 659 BC, as Hela reaches adulthood, she begins to fight alongside her father, Odin. Over the years, together, they build Asgard's empire across the realms and build its glory. By the time Odin decides to stop his conquest after realising peace is the true way to unite the Nine Realms, Hela's ambition has grown too large, and coupled with her tremendous powers, she ultimately tries to take the throne and Odin is forced to battle and imprison his daughter in the realm of Hel after defeating her, for the safety of the Asgardians.
There she was kept for nearly 2700 years, until her escape in 2017. Odin would spend the next several centuries burying her history and pretending she never existed. When his next child, Thor, was born over 1600 years later, he claimed him to be his actual firstborn.
950 AD (Massacre of the Valkyrie)
After nearly 1600 years of imprisonment, Hela attempts to escape from her prison of Hel. Her father and the man who imprisoned her, Odin, sends his army of Valkyries on their flying steeds to keep her at bay. They attempt to prevent her escape, but Hela is too much for them and she massacres the whole army, save for Brunnhilde, who is saved by one of her teammates. Odin intervenes and enters Hel. The All-Father manages to overpower and re-imprison Hela.
Brunnhilde forsakes Asgard and escapes to the junk planet of Sakaar, where she intends to live out the rest of her days drinking and salvaging, attempting to leave her old Valkyrie life behind her.
Thor Odinson is born to Odin Borson and Frigga, and claimed to be Odin's firstborn child, and thus the heir to the throne of Asgard. He is not told about his imprisoned older sister until the day of his father's death in 2017.
Battle of Tønsberg: The Frost Giants of Jotunheim attempt to conquer Midgard (Earth), starting their invasion in Tønsberg, Norway. The Asgardians hear of the attack, assemble their army and prepare for battle. Odin leads the Asgardian army in an epic battle against the Frost Giants, to repel their invasion and protect Midgard
Jotunheim’s Frost Giants invade Tøsberg, Norway in an attempt to conquer Midgard (Earth). Odin leads the Asgardian army against the Frost Giants to defend Midgard. Odin also discovers an abandoned Jotunheim infant, adopting him, and raising him alongside his own son Thor with the given name, Loki. Odin negotiates a truce with the Frost Giant king, Laufey.
A son is born to Laufey, king of the Frost Giants. He is left out to die in Jotunheim. The Asgardians force the Frost Giants back to Jotunheim, where Odin discovers an abandoned Frost Giant infant. He adopts the child, names him Loki, and raises him alongside his own son, Thor. He later negotiates a truce with Jotunheim's king, Laufey.
1018 AD (Thanos)
Thanos is born on planet Titan. Years later, Titan is threatened by a looming catastrophe as the planet is no longer able to sustain its growing population. Thanos proposes that 50% of Titan’s people be euthanized (killed) immediately to make room for the survivors to rebuild. His ideas are rejected as insane and he is banished from Titan.
Eventually, war and starvation lead to the collapse of Titanian civilisation, and the planet is laid waste, leaving Thanos the last survivor of his race. This convinces him not only that he was right, but that the entire universe will eventually face the same fate. He becomes obsessed with preventing this by killing half of all life in the entire universe.
Over the following centuries, Thanos becomes a powerful galactic warlord with a vast interstellar empire under his direct control. He routinely conquers whole planets, murdering half their populations as part of his quest to preserve the balance of life in the universe. He also frequently adopts orphans from each conquered race, raising them as the Children of Thanos, who command his forces.
Odin hides the Tesseract in Tønsberg, Norway. This is eventually forgotten and the Tesseract is considered lost.
Thanos conquers the planet Zen-Whoberi. After executing half of its population, he adopts one of the survivors, an eight year-old girl named Gamora.
In Asgard, Thor makes war on the Frost Giants in Jotenheim against Odin’s wishes. During the battle, Loki learns he is Frost Giant. Odin banishes Thor to Earth as punishment for his defiance and strips him of his right to use the hammer Mjølnir.
In Asgard Loki is angry at having been lied to about his origin and plots to overthrow Odin. On Earth, Thor meets Jane Foster and Eric Selvig, uncovers Loki’s plan, and returns to Asgard to save the day. During the fight, Asgard’s Bifrost Bridge, a wormhole Asgardians use to travel throughout the Nine Realms, is destroyed and Loki presumed dead.
The latest Convergence of the Nine Realms causes the pocket dimension containing the Aether to open into our world, creating bizarre scientific anomalies around it. While investigating, Jane Foster comes in contact with the Aether, which bonds to her in a process that will eventually kill her. Thor then brings her to Asgard in hopes the advanced medical care found there will save her.
The Dark Elves attack Asgard and Earth in an attempt to reclaim the Aether, and Thor enlists Loki’s help to stop the Elves and remove the Aether from Jane. During the battle, Loki fakes his death again. Thor brings the Aether back to Asgard. Meanwhile, Loki has disguised himself as Odin and now rules Asgard in secret.
Shortly after, it’s decided that having two Infinity Stones in the same place is too dangerous, so Asgard gives the Aether to The Collector, who lives on Knowhere, for safekeeping.
After spending a couple of years looking for a way to stop Ragarok (he had a vision during the fight against Ultron), Thor finally learns that Loki deposed Odin and returns to Asgard. The pair go to Earth to locate Odin, where they’re aided by Dr. Strange. Odin reveals he is dying, tells Loki and Thor about Hela, and warns his death will end her imprisonment.
Hela arrives on Earth, destroys Mjølnir, and exiles Thor and Loki, who wind up on planet Sakaar. On Sakaar, Loki ingratiates himself into The Grandmaster’s social circle, while Thor is forced to fight in The Grandmaster’s gladiator games. Thor finds encounters the Hulk, who has become The Grandmaster’s champion and Sakaar’s favorite fighter.
Eventually, Thor convinces Hulk and Scrapper 142, the last surviving Valkyrie, to help him fight Hela, who has conquered Asgard in his absence.
Back on Asgard, Hela gouges out Thor’s eye. But with the help of Valkyrie, Hulk and Loki, Thor manages to defeat Hela by actually letting Ragnarok begin. Asgard is destroyed, but the Asgardians survive as refugees on a massive spaceship. In the escape, Loki takes the Tesseract with him.
Around this time Thanos invades and devastates Xandar, and takes possession of the Power Infinity Stone.
As the Asgardians, with Thor as their new king, head to Earth, they’re intercepted by a massive spaceship. That ship is the Sanctuary II, commanded by Thanos.