From the introduction:
The most important aspect that anyone will need to know is this: Suntarynn was once a normal planet, like most other campaign settings, but is one no longer. The world was in the process of dying. The gods ripped the worlds apart, saved the good parts, and reformed them into another world. (This event is known among the inhabitants of Suntarynn as The Reshaping.) This new world, however, is simply a flat plane that floats in a misty void. The void, the world, the weather within the world - everything is kept together and running properly by the gods or by those appointed by them.