3437 P.X.E. is the post-apocalyptic alternate timeline Silver the Hedgehog comes from, two-hundred years into the future of Mobius Prime's timeline.
Due to the supposed treachery of one of the legendary Freedom Fighters, the entire team was destroyed and, without them, the future was doomed. Because of the dire state of the world brought about by devastation from Dr. Eggman and the rise of Ixis Naugus' Ixis Resurgence, Silver repeatedly travels through time attempting to find the apparent traitor among the Freedom Fighters and prevent whatever events lead to the ruined future. Despite Silver's efforts, it has been seen that even when he succeeds in preventing some form of disaster in the past, 3437's present remains ruined, and thus he believes that the traitor is the most important factor. At one point, Silver described his world as having "Pockets of civilization struggling against a global sea that seems to have a grudge." It seems that most civilizations have been destroyed; many cities appear as empty ruins and the Space Colony ARK at some point had crashed into the planet, remaining a long-burning husk. Records of the past are scarce and subject to change due to Silver's efforts to rewrite history.
Space Colony ARK
Silver the Hedgehog