The Overworld was previously the realm of the gods and the afterlife of mortals in the United Plane. It was destroyed during the Shattering, but the void that consisted of its former space was colonized by the new gods as a means of creating their own afterlife.
The Overworld is home to the gods, goddesses, overworld beings (such as archons and angels) aswell as "good" mortal souls that have passed on to the correct location.
The overworld is split into tiers of accommodation depending on how much good someone has done, or how time they have spent enlightened.