The Himalayas, which are often called "The Roof of the World", contain the greatest area of glaciers and permafrost outside of the poles. Ten of Asia’s largest rivers flow from here, and more than a billion people’s livelihoods depend on them. Together, the Himalayan mountain system is the world's highest, and home to the world's highest peaks, the Eight-thousanders, which include Mount Everest and K2. To comprehend the enormous scale of this mountain range, consider that Aconcagua, in the Andes, at 6,962 metres (22,841 ft) is the highest peak outside Asia, whereas the Himalayan system includes over 100 mountains exceeding 7,200 m (23,600 ft).