Before history began, all of existence was threatened by a creature known as Rovagug the Devourer. Even the gods were afraid of him, and ultimately they banded together and yet were still unable to destroy him. In the end they settled for imprisoning him in the centre of the planet known today as Golarion. People of other worlds call this planet “The Cage” and say that no sane person visits that world.
The Cage has one moon, called Somal by its inhabitants.