A vast area of complete aridity created where Jak'ra touched down on the Oerth shortly after its creation. His immense power scorched the ground to sand, so nothing will ever grow there. Some myths suggest he landed at the area now known as The Glassed Lands, resulting in the strong background magical energies. All in the desert is sand and rocks. Do not go here unless you like getting eaten by Harpies, beaten to death by Greenskins or Gnolls, crushed by an absent-minded tarkus or dying of thirst and starvation.
On the edge of the desert you can find attempts for civilisation to take on the natural world. Most end up like Tavró and are quickly swallowed by the desert.
Features rather heavily in the campaign A Gathering Storm.