Ü-Tsang or Tsang-Ü, is one of the three traditional provinces of Tibet, the other two being Amdo and Kham. Geographically Ü-Tsang covered the central and western portions of the Tibetan cultural area, including the Brahmaputra River watershed, the western districts surrounding and extending past Mount Kailash, and much of the vast Changtang plateau to the north. The Himalayas defined Ü-Tsang's southern border. The present Tibet Autonomous Region corresponds approximately to what was ancient Ü-Tsang and western Kham.