The Tibet Autonomous Region is located on the Tibetan Plateau, the highest region on earth. In northern Tibet elevations reach an average of over 4,572 metres (15,000 ft). Mount Everest is located on Tibet's border with Nepal.
Physically, the Tibet AR may be divided into two parts, the "lakes region" in the west and north-west, and the "river region", which spreads out on three sides of the former on the east, south, and west. Both regions receive limited amounts of rainfall as they lie in the rain shadow of the Himalayas, however the region names are useful in contrasting their hydrological structures, and also in contrasting their different cultural uses which is nomadic in the lake region and agricultural in the river region.[12] On the south the Tibet AR is bounded by the Himalayas, and on the north by a broad mountain system. The system at no point narrows to a single range; generally there are three or four across its breadth. As a whole the system forms the watershed between rivers flowing to the Indian Ocean – the Indus, Brahmaputra and Salween and its tributaries – and the streams flowing into the undrained salt lakes to the north.
Physically, the Tibet AR may be divided into two parts, the "lakes region" in the west and north-west, and the "river region", which spreads out on three sides of the former on the east, south, and west. Both regions receive limited amounts of rainfall as they lie in the rain shadow of the Himalayas, however the region names are useful in contrasting their hydrological structures, and also in contrasting their different cultural uses which is nomadic in the lake region and agricultural in the river region.[12] On the south the Tibet AR is bounded by the Himalayas, and on the north by a broad mountain system. The system at no point narrows to a single range; generally there are three or four across its breadth. As a whole the system forms the watershed between rivers flowing to the Indian Ocean – the Indus, Brahmaputra and Salween and its tributaries – and the streams flowing into the undrained salt lakes to the north.
The river region is characterised by fertile mountain valleys and includes the Yarlung Tsangpo River (the upper courses of the Brahmaputra) and its major tributary, the Nyang River, the Salween, the Yangtze, the Mekong, and the Yellow River. The Yarlung Tsangpo Canyon, formed by a horseshoe bend in the river where it flows around Namcha Barwa, is the deepest, and possibly longest canyon in the world.[13] Among the mountains there are many narrow valleys. The valleys of Lhasa, Shigatse, Gyantse and the Brahmaputra are free from permafrost, covered with good soil and groves of trees, well irrigated, and richly cultivated.