n.
or the Himalaya
Mountain system, southern Asia.
It forms a barrier between the Tibetan Plateau to the north and the plains of the Indian subcontinent to the south. It constitutes the greatest mountain system on earth and includes 30 mountains rising to heights above 24,000 ft (7,300 m), including Mount Everest . The system extends some 1,500 mi (2,400 km) from east to west and covers about 230,000 sq mi (595,000 sq km). It is traditionally divided into four parallel ranges: from north to south, the Trans-Himalayas, the Great Himalayas (including the major peaks), the Lesser Himalayas (including peaks of 7,00015,000 ft, or 2,0004,500 m), and the Outer Himalayas (including the lowest peaks). Between the eastern and western extremities of the broad Himalayan arc lie several Indian states and the kingdoms of Nepal and Bhutan. It acts as a great climatic divide, causing heavy rain and snow on the Indian side but aridity in Tibet , and represents at many points a virtually impassable barrier, even by air. The mountains' glaciers and snows are the source of 19 major rivers, including the Indus , Ganges , and Brahmaputra .