The Kostaigne Desert is the large region of Invinni to the northwest of Aesedra. Desert is perhaps a misnomer as only a fraction of this vast land could be climatically described as a desert. Geographically, it is the land bordered on the west by the Grey Mountains, to the north by the Great Northern Sea, to the east by the Solscami and the sparsely inhabited northern fringes of the Wind Kingdom. Celobsil lies to the south. In size, its area is almost as big as Aesedra, though having nowhere near the population.
The largest river in the world, the Usymna River has its headwaters in the Great Scarp and flows northwest for nearly 5500 miles through a broad valley until it reaches Icehell Bay. Most people who dwell in these cold lands usually do so within a week's travel of the river. The northern half of the river freezes over in winter.