Sherpas are to mountaineering what Kalenjins are to marathoning. Climbing the world's highest peaks is a sport pioneered by westerners, but Sherpas, an ethnic group who live in the Himalaya, dominate it. They hold the world record for most Everest ascents—Apa Sherpa and Phurba Tashi Sherpa both summited the peak 21 times—and the majority of speed summiting records. Pemba Dorje climbed from Everest's South Base Camp to summit with supplemental oxygen in eight hours and ten minutes, while Kazi Sherpa completed the feat without supplemental oxygen in 20 hours and 24 minutes.
Turns out that Sherpas bloom into incredible endurance athletes at high altitudes. From my recent Vice story: