Ilemi Triangle, triangular-shaped region, c.10,000 sq km (3,860 sq mi) in area, at the NW corner of Lake Turkana, E Africa. It borders South Sudan (W), Ethiopia (E) and Kenya (S). A disputed territory, it is claimed by both Kenya and South Sudan; Kenya has de facto control of the region. Sparsely settled, the Ilemi Triangle has areas of mountains, dry-season pasture lands, and swamps, and may have petroleum deposits. The inhabitants are the nomadic Turkana and other pastoral peoples. Disputes regarding the ownership of the Ilemi Triangle date to the colonial partition of Africa.