Dark Sun Jump

From the introduction:

You've been dropped on the planet of Athas, this is a dying world that's barely holding on. It orbits what looks to be a Red Giant, this star is much closer than the sun back on Earth. On this death world, there is ancient civilizations lead by ancient and deadly Sorcerer-Monarchs. They jealously guard their kingdoms inside vast city-states, which only handful of these nations dot the landscape. To the west of this "Tableland" is The Dead Lands where nothing but undead. To the east is the Crimson Savannah, a vast area filled with razor-sharp bamboo forest but there The Kreen rule their empire; to the south is the Sea of Silt.