The oldest of the four main schools of Tibetan Buddhism. Its doctrines and practices derive from teachings brought to Tibet during the period of the ‘First Propagation’ in the 8th century ce by the scholar-monks Śāntarakṣita and Kamalaśīla, the tantric yogin Padmasambhava, as well as the monks Vimalamitra and Vairocana, who were all based at Samyé.the first Tibetan monastic centre. The characteristic Nyingma teachings focus on Dzogchen and a separate collection of tantras not included in the later standard compilation of the Kanjur by Butön rin-chen-grup. The Nyingma school gained its name retrospectively during the 11th century ce to distinguish it from teaching lineages transmitted during the ‘Second Propagation’ period. As well as its unique classificatory system of Buddhism, the nine vehicles, the Nyingma school also has a tradition of continuous revelation of hidden teachings known as terma.which include such works as the ‘Tibetan Book of the Dead’ (Bar-do thos-grol). Many Nyingma teachings were systematized by Longchenpa (1308–64) and Jigmé Lingpa (1730–98). Although many Nyingma adherents were either lay-persons or yogins.there has also been a continuous monastic tradition. Nyingma monks use red ceremonial hats from whence they derive their popular name, the ‘Red Hat’ school.