Earth-X

Earth-X is a parallel dimension version of our own Earth (in classification terms, this Earth is called "Earth-A"). It differs from Earth-A in the landmass takes a pangean shape, in one supercontinent, causing society to grow in a much different shape and technology to advance at an extreme rate. Earth-X was first discovered during the First Crisis Event of 1985.

Notable Differences
As the technology of the planet is at a much higher level than that of our Earth, by 1985, our only real chance to see this other Earth, Earth-X had teleportation, interdimensional technology, far more technologically advanced vehicles and weaponary and advanced robotics. An example of what would be classed as an "early" piece of Earth-X technology, the oldest known Earth-X object found on Earth-A, is the often-malfunctioning Blade of Aeons.

It is also thought that Earth-X has a much more tough climate and lack of water, as much of the landmass has no close access to water. As such, humanity may be one of the only surviving species on Earth-X.

Notable Figures
Earth-X played as a main figure in the First Crisis, with a large number of the superpowered population of Earth-X (it is unknown if they have superhumans in the same way we do, as they may have evolved to all have powers) teleporting America in the turmoil, adding to it or taking refuge. Of those who came to Earth-A, there are few we know the names of, but famed among them is the easily-angered Glorihound, the leader of an attack force of Earth-X supermen. Post-Crisis, however, only one name from Earth-X remains in the memory of the people as a hero to prove that alternate dimensional Earth wasn't all bad; The Heretic.

Though not much is known about this planet, or those who came from there, there is one thing known for a fact: Earth-X is not an ally.