Yak. Yak (Bos grunniens), yakRuss Kinne/Photo Researchers long-haired, short-legged oxlike mammal that was probably domesticated in Tibet but has been introduced wherever there are people at elevations of 4,000–6,000 metres (14,000–20,000 feet), mainly in China but also in Central Asia, Mongolia, and Nepal.May 22, 2014