The Himalayas are the best (0) KNOWN mountain range the world and Mt Everest, with a of 8,800 m is the highest mountain. Since Edmund Hillary made the first ascent in 1953 mountaineers many countries have managed to climb to the peak.
Normally they to take oxygen cylinders to help them breathe and other special equipment, including ropes to themselves to each other. It's a dangerous sport and many people have lost their lives, not just on the way but during the descent as well.