A distinctive form of Buddhism that draws heavily on Mahayana Buddhism, which was introduced to Tibet in the seventh century. Tibetan Buddhism incorporates the esoteric tradition of tantra of Vajrayana Buddhism, features of ancient Bon shamanism, and monastic disciplines of early Theravada Buddhism. Avalokiteshvara, the Bodhisattva of Compassion, is particularly revered in Tibetan Buddhism and each Dalai Lama, the spiritual and temporal leader of Tibet, is believed to be his reincarnation. Worship includes the recitation of mantras and prayers, and the singing of hymns accompanied by the playing of drums and horns. The Tibetan canon of scripture includes the 'Kangur' and the 'Tenjur;' the Tibetan Book of the Dead (Bardo Thödröl) describes consciousness between death and rebirth. There are four major schools: Nyingma, Sakya, Kagyu, and Geluk. The religion is sometimes incorrectly called lamaism, a Western term not used by Tibetan Buddhists themselves.