Complex sentence: Lamaism, in Tibet, is the body of religious doctrine and institutions that were derived from Mahayana Buddhism, which was introduced in the 7th century and married to both the Shamanistic Bön Religion (see Shamanism), and Tantric elements.
Split into simpler sentences: Lamaism, in Tibet, is the body of religious doctrine and institutions that were derived from Mahayana Buddhism, which was introduced in the 7th century. This Buddhism was married to both the Shamanistic Bön Religion (see Shamanism), and Tantric elements.