The Ash is the home of the deities. It is a world underneath the mortal world, and it is made up almost exclusively of fields comprised of soot and ash. The only exception to this is there is a single lava pool around which sit the gods on impeccably clean glass thrones. Soot and ash cling to all who travel through, even the gods. The gods look into the pool of lava to view the mortal world above them, and they can enter it to cross into the realm of the mortals.
The mortal world does not have a name such as The Ash. It is only known as the world where mortals live.