When it comes to sheer altitude, no mountain range rivals the Himalayas. Stretching 2,400 km (1,500 miles) across Asia, they form a colossal arc along the northern edge of the Indian subcontinent, separating the plains of India from the Tibetan Plateau—the "Roof of the World."
The Himalayas boast the planet's highest summit: Mount Everest (8,848.86 m / 29,031.7 ft). But Everest is just one of over 100 peaks exceeding 7,200 m (23,600 ft), including K2 (though K2 is in the Karakoram, often grouped), Kangchenjunga, Lhotse, Makalu, and Annapurna.
The range is the direct result of the ongoing collision between the Indian Plate and the Eurasian Plate, a process that began ~50 million years ago and continues today (the Himalayas still rise ~5 mm/year). This continental collision crumpled the crust, thrusting marine sediments (including fossil-bearing limestone on Everest's summit) to the stratosphere.
The Himalayas span or border five nations:
The Himalayas are Asia's water tower. Their glaciers and snowfields feed the Indus, Ganges, Brahmaputra, Yangtze, Mekong, Salween, and Irrawaddy rivers—supporting nearly 2 billion people downstream. They also create the monsoon barrier that shapes the climate of the entire subcontinent.
In every sense—geologic, climatic, cultural, spiritual—the Himalayas are the defining high ground of our planet.