The yak is the nomad’s most precious commodity, the source of all his ‘nor’ or wealth and the main bovine on the Tibetan Plateau. A distant cousin of the Indian buffalo and the American bison, the yak is a heavily built horned animal with a bulky frame, sturdy legs, rounded cloven hooves and a placid disposition. Characterized by long shaggy hair that hangs down below its belly and a dense down-like undercoat, it also holds a hidden treasure; a precious brown fiber the Tibetans call khullu that insulates it from the bitter winter cold. The domestic yak or Bos Grunniens (grunting ox) is a direct descendant of the much larger wild yak, Bos Mutus (mute ox), now an endangered species found mainly in the Northern Plains of Central Tibet. The yak has adapted to high altitudes and thrives at 3000 meters and above. There are presently 13 million yaks on the Tibetan Plateau and beyond, into Mongolia, Eastern Russian, the Himalayan regions and parts of Central Asia. They live in herds of up to 400 head, their meat and milk sustaining about 3 million nomads.Tibetan nomads use their yaks for meat, dairy products and khullu. Hardy and sure footed, they used to be an important element in trade and transport, but since the advent of motor roads have now been largely replaced by faster trucks and pick-ups.