This reality was accidentally created by Legion, son of X-Men leader Professor Charles Xavier and Israeli diplomat Gabrielle Haller. Legion believed that the only way to bring peace to humans and mutants was to kill Magneto before he incited the anti-mutant movement. He traveled back to a time when Xavier and Magneto both lived in Israel and worked at a hospital, taking the X-Men Storm, Iceman, Bishop, and Psylocke with him.
The trip through time gave everyone amnesia, however. The other X-Men attacked Legion. Legion tried to stab Magneto with a psi-blade, but Xavier shielded Magneto and died instead. By killing his own father, Legion made his own existence impossible. The M'Kraan Crystal resolved the paradox by restructuring reality. All the X-Men vanished from that reality, and a new reality came into existence. Bishop, already displaced in time, remained, but the chronal backlash fractured his mind. He would wander the earth for the next twenty years.
The super-powered fight also attracted the attention of Apocalypse.
Apocalypse believed in natural selection, the "survival of the fittest". By this reasoning, super-powered beings deserved to run the world. When he saw such beings in action twenty years early, he got an early start on his campaign for world domination. Without heroes such as the Fantastic Four, Spider-Man, and the Avengers, there was no one to stop him.
The only opposition was Magneto, who took up Xavier's cause and brought together the X-Men.
The world powers, as well as the face of the Earth, were drastically changed as a result of Apocalypse's war against normal humans. The world was divided between two superpowers: Apocalypse in North America and the Human High Council everywhere else. Both groups claimed to act in the best interest of their genetic breeds.
Militarily, the sides were in a stalemate. North America was protected by a sea wall. The High Council had a large cache of nuclear weapons. As in our own Cold War, both sides were calling for peace while plotting the other's destruction. Any incident could spiral out of control and lead to the annihilation of all humanity.
During this period, Apocalypse had various ties with nonhuman groups: some favorable, as with the Inhumans; some unfavorable, as with invaders from the Negative Zone; and some unforgivable, as with the natives of Planet Poppup, who were subjected to medical experiments.
Below are the various regions of the Age of Apocalypse:
The southern part of the continent was divided between Apocalypse and his four horsemen. These provinces were:
Central America disappeared, possibly to make room for the sea wall (the exact means and motive were never disclosed).
There was an Infernal Gallop to Avalon in the seas not far from Bermuda.
South America became known as "The Atrocity Zone." Brazil was obliterated by a nuclear strike. There may have been an Infernal Gallop on the west coast.
The people who escaped from the United States gathered here. They were governed by the Human High Council (also known as the Eurasian High Council). The region was defended by Sentinels, created by Bolivar Trask, and a nuclear arsenal large enough to destroy the entire North American continent. Areas of interest included:
Asia was a wasteland. Japan was decimated by Apocalypse. The Middle Eastern oilfields were nuked.
Avalon (the Savage Land in the Marvel Universe) was a lost world independent of Apocalypse and the Human High Council and was a safe haven for mutant and human alike.
The beginning of the end came when the X-Men discovered Bishop, the only person on earth who remembered the way reality should have been. After learning of the existence of this alternate reality (backed up by Magneto's own memories of Xavier's death), the X-Men embarked on a quest to stop Apocalypse once and for all and to restore the timeline to its intended course. This was a main focus of the individual story arcs in each of the Age of Apocalypse titles.
Followed the adventures of the other half of the X-Men (Quicksilver, Exodus, Dazzler, Iceman, Storm, and Banshee) assisting the Sentinels in evacuating human survivors on the east coast to Eurasia. Also told the tale of Magneto and Bishop's capture and Apocalypse learning of Magneto's quest to restore history.
Gambit and his X-Ternals (Jubilee, Strong Guy, Sunspot), with the help of mutant teleporter Lila Cheney, traveled to the distant Shi'ar galaxy to steal the M'Kraan Crystal and bring it to Earth. It was the first item required to restore history. Strong Guy, a traitor in the group's midst, gave it to Apocalypse.
Followed the tale of Apocalypse's elite police, and its leader Cyclops's eventual mutiny and his freeing of the slaves with the aid of Jean Grey.
Clone created from the DNA of Cyclops and Jean Grey who, under the tutelage of Forge, discovered his origins thanks to the manipulation of Sinister. He was created to destroy Apocalypse, and he joined Magneto's X-Men in their final battle against Apocalypse.
Told the tale of Mikhail, the lost horseman, and his involvement in Eurasia. He plotted to take over the continent and assassinate the Human High Council, but was stopped by the combined efforts of normal humans: Victor von Doom, Donald Blake, Gwen Stacy, Susan Storm, and Ben Grimm.
The final battle in Apocalypse's stronghold for the M'Kraan Crystal saw many casualties, and marked the deployment of both Apocalypse's sea wall defense perimeter and the Human High Council's nuclear arsenal, which threatened to destroy the whole world.
During the battle, Magneto battled Apocalypse to the death, ripping the mutant in half with his magnetic powers.
Also during the battle, Bishop, Destiny, and Illyana traveled into the M'Kraan Crystal. Destiny and Illyana's powers helped send Bishop back in time to the point where Xavier was about to be killed by Legion. Bishop managed to stop Legion, and the two were consumed by the backlash of psi-energy. The Age of Apocalypse, and all memory of it, was seemingly erased with the prevention of Xavier's assassination.
The following characters managed to escape the Age of Apocalypse before its apparent destruction:
Years later, it developed that the Age of Apocalypse timeline did not disappear. Sinister claimed to Magneto that he was responsible. Everyone else believed it to be Magneto, who took the credit in order to be the figurehead for mutant-kind. He pledged to keep Sinister's secret, which meant turning a blind eye to his experiments.
Over the coming years, Magneto and his X-Men rebuilt the world and freed all the surviving humans from the slave pens. The old world system was reestablished, and Magneto was elected the head of Mutant Affairs in America.
Magneto opened a school for mutants in Xavier's mansion and began hunting down all of Apocalypse's surviving henchmen and bringing them to justice. Under constant pressure, Magneto finally went after Sinister.
The ensuing confrontation revealed that the timeline had actually been saved by Jean Grey, the genetic descendant of Alpha, the first mutant. Her enhanced powers (the Phoenix Force) stopped the weapons from destroying the world and maintained reality. The X-Men won the battle and freed Jean from Sinister's control.
Shamed by his lie, Magneto turned himself over to the authorities in a self-imposed punishment for his deception. The X-Men vowed to remain together and fight for equal rights for humans and mutants.
The first listed title is from Age of Apocalypse; the second is the new title in Earth-616's continuity.
Comics:Age of Apocalypse