In Tibetan buddhism, Yama is a wrathful protector who presides over the cycle of death and rebirth. He has a buffalo head and stands on a male buffalo lying over a corpse. He is adorned with the wrathful ornaments (five-skull crown, bone jewellery, garland of severed heads) and wears a tiger skin as a loin cloth. In his right hand he may hold a bone stick or a sword, in his left hand he may have a lasso or a mirror.
This could in fact be Vajrabhairava, who may hold a flaying knife and a skull cup at heart level.
The shape of the scarf and the cross belt indicate a Chinese influence and help date the sculpture from around the 16th century onwards.
Here, the raised hair and the head seem out of proportion with the unusually slender body.