Atlantis

Atlantis was the name given to a legendary "lost continent" that disappeared from the planet Terra approximately four thousand years ago. The belief on Terra was that the island disappeared and sank beneath the ocean, but Atlantean technology had instead opened a wormhole linking the planets of Katia and Terra. In the space of a single day and night, the island kingdom fell through the wormhole and surfaced on Katia, where it remains to this day.