The Himalaya Range or Himalaya Mountains usually called the Himalayas or Himalaya, is a mountain range which crosses Pakistan, Nepal, Tibet, Bhutan and India. By extension, it can also refer to the massive mountain system that additionally includes the Karakoram, the Hindu Kush, and other lesser ranges that extend out from the Pamir Knot. Some of the world's major river systems arise in the Himalayas, and their combined drainage basins are home to some 3 billion people (almost half of the Earth's population) in 18 countries. The Himalayas have profoundly shaped the cultures of South Asia; many Himalayan peaks are sacred in Hinduism, Buddhism and Sikhism.
Geologically, the Himalayas originate from the northward movement of the Indian tectonic plate at 15 cm per year to impact the Eurasian continent, with first contact about 70 million years ago, and with movement continuing today. This caused the formation of the Himalayan arc peaks: the lighter rocks of the seabeds of that time were easily uplifted into mountains. An often-cited fact used to illustrate this process is that the summit of Mount Everest is made of marine limestone.