Tarim Basin, vast depression drained by the Tarim River in the Uygur Autonomous Region of Xinjiang, western China, covering about 350,000 square miles (906,500 square km) and enclosed by the Tien Shan (mountains) to the north, the Pamirs to the west, the Kunlun Mountains to the south, and the Altun Mountains to the east. The climate is extremely dry since the mountains block out moist air from the sea. Annual rainfall is less than 4 inches (100 mm). The salt lake and marshland of Lop Nur lies at the eastern end of the basin. In the centre of the basin is the Takla Makan Desert, which covers an area of 132,000 square miles (342,000 square km). Several water conservation projects have been built in the Tarim Basin, including a canal that irrigates some 50 square miles (130 square km) of farmland.