Ili River, river in western Uygur Autonomous Region of Xinjiang, China, and southeastern Kazakhstan. It is 870 miles (1,400 km) long and drains the basin between the Tien Shan range to the south and the Borohoro (Poluokenu) Mountains to the north. Both ranges are extremely high. The drainage basin of the Ili and its principal tributaries—the Kax (Kashi), Künes, and Tekes rivers—is rugged and mountainous, the axes of the mountain systems running approximately west-east. Just within the Chinese frontier the valley broadens out to form a fertile plain around Yining (Kuldja). The Ili River flows westward into Kazakhstan, to the north of Almaty, and eventually discharges into Lake Balkhash. The Ili valley is much wetter than most of Chinese Central Asia and has a large settled farming population, predominantly engaged in cultivating wheat. The uplands support large numbers of sheep, goats, and horses.