Geography of Tibet

Tibet is a region of central Asia. It is often called "the roof of the world", comprising table-lands averaging over 4,950 metres above the sea with peaks at 6,000 to 7,500 m, including Mount Everest. It is bounded on the north and east by China, on the west by the Kashmir Region of India and on the south by Nepal, Bangladesh and Bhutan. Most of Tibet sits atop a geological structure known as the Tibetan Plateau which includes the Himalaya and many of the highest mountain peaks in the world.

Physically, Tibet may be divided into two parts, the "lake 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 (see map of the land use patterns of historic Tibet)

The lake region extends from the Pangong t'so (t'so = lake) in Ladakh, near the source of the Indus River, to the sources of the Salween, the Mekong and the Yangtze. This region is called the Chang Tang (Byang sang) or 'Northern Plateau' by the people of Tibet. It is some 1100 km (700 mi) broad, and covers an area about equal to that of France. Due to its great distance from the ocean it is extremely arid and possesses no river outlet. The mountain ranges are spread out, rounded, disconnected, separated by flat valleys relatively of little depth. The country is dotted over with large and small lakes, generally salt or alkaline, and intersected by streams, and the soil is boggy and covered with tussocks of grass, thus resembling the Siberian tundra. Salt and fresh-water lakes are intermingled. The lakes are generally without outlet, or have only a small effluent. The deposits consist of soda, potash, borax and common salt. The lake region is noted for a vast number of hot springs, which are widely distributed between the Himalaya and 34° N., but are most numerous to the west of Tengri Nor (north-west of Lhasa). So intense is the cold in Tibet that these springs are sometimes represented by columns of ice, the nearly boiling water having frozen in the act of ejection.

The river region comprises the upper courses of the Brahmaputra, the Salween, the Yangtze, the Mekong, and the Yellow River. Amidst the mountains there are many narrow valleys. Whereas the lake region is an arid and wind-swept desert, the river region is characterized by fertile mountain valleys. The valleys of Lhasa, Shigatse, Gyantse and the Brahmaputra are covered with good soil and groves of trees, are well irrigated, and richly cultivated.

The valley of the Brahmaputra is the great arterial valley of southern Tibet. On the south it is bounded by the Himalayas, 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.