The Himalaya Mountains stretch 1500 miles across parts of Afghanistan, Pakistan, India, Nepal, Tibet, and Bhutan. They were formed 40-50 million years ago through the collision of the Indian and Eurasian tectonic plates, causing the Earth's crust to fold and thrust upward. The mountains continue growing as the tectonic plates still move. Home to 9 of the 14 tallest peaks in the world, including Mount Everest at over 29,000 feet tall, the Himalayas are also where many of the world's major river systems originate, supplying water to almost half the global population.