The pre-Buddhist religion of Tibet, characterized by the belief in a supreme sky god and a hierarchy of good and evil spritis, gods, demons, and ghosts. Elaborate ritual, including animal, or even human, sacrifice, abounded; religious practice was presided over by a class of shamans (see shamanism), pries-magicians who could influence the spirits by means of white or black magic, even being able to open the gate between heaven and earth. It was absorbed into Tibetan Buddhism, to which it lent a very individual character.