Tibet is located on the Tibetan Plateau, the world's highest region. Most of the Himalaya mountain range lies within Tibet. Its most famous peak, Mount Everest, is on Nepal's border with Tibet. The average altitude is about 3,000 m in the south and 4,500 m in the north.

The atmosphere is severely dry nine months of the year, and average snowfall is only 18 inches, due to the rain shadow effect whereby mountain ranges prevent moisture from the ocean from reaching the plateaus. Western passes receive small amounts of fresh snow each year but remain traversable all year round. Low temperatures are prevalent throughout these western regions, where bleak desolation is unrelieved by any vegetation beyond the size of low bushes, and where wind sweeps unchecked across vast expanses of arid plain. The Indian monsoon exerts some influence on eastern Tibet. Northern Tibet is subject to high temperatures in the summer and intense cold in the winter.

Tibetan cultural influences extend to the neighboring states of Bhutan, Nepal, adjacent regions of India such as Sikkim and Ladakh, and adjacent provinces of China where Tibetan Buddhism is the predominant religion.

The Indus, Brahmaputra rivers originate from a lake (Tib: Tso Mapham) in Western Tibet, near Mount Kailash. The mountain is a holy pilgrimage for both Hindus and Tibetans. The Hindus consider the mountain to be the abode of Lord Shiva. The Tibetan name for Mt Kailash is Khang Rinpoche.