Earth-4126 is also known as the Alterniverse.
At one point, Earth-4126 was like any other Earth, with heroes and villains, along with alien races. However, it was drastically changed after a war-like alien race called the Celestials arrived. The heroes and villains of Earth teamed up to defeat the race of god-like aliens, who wished to destroy their world. The heroes barely managed to win, but the planet paid the price. Humanity managed to adapt to its new environment, though it was not easy. The war also spawned many new species, that live on what used to be Australia. Very few humans still live on the Savage Islands.