A yak transports, according to the season, between 40 and 60 kg. It is one of the only richnesses which the Tibetans have. Its skin and its wool are used to manufacture clothes, its dungs to heat the houses, whereas its milk and its meat are used as food. Living at an altitude ranging between 3500 and more than 5000 meters, the yak is economic and nourishes with almost anything, being satisfied sometimes with lichens.