The Tibetan Plateau , also known in China as the Qinghai–Tibet Plateau or the Qing–Zang Plateau or Himalayan Plateau, is a vast elevated plateau in Central Asia and East Asia, covering most of the Tibet Autonomous Region and Qinghai in western China, as well as Ladakh and Lahaul & Spiti (Himachal Pradesh) in India.

It stretches approximately 1,000 kilometres (620 mi) north to south and 2,500 kilometres (1,600 mi) east to west. It is the world's highest and largest plateau, with an area of 2,500,000 square kilometres (970,000 sq mi) (about five times the size of Metropolitan France). 

With an average elevation exceeding 4,500 metres (14,800 ft) and being surrounded by imposing mountain ranges that harbor the world's two highest summits, Mount Everest and K2, the Tibetan Plateau is often referred to as "the Roof of the World".

The Tibetan Plateau contains the headwaters of the drainage basins of most of the streams in surrounding regions. 

Its tens of thousands of glaciers and other geographical and ecological features serve as a "water tower" storing water and maintaining flow. 

According to en.wikipedia