There are four principal schools within modern Tibetan Buddhism:
Nyingmapa ("School of the Ancients") is the oldest of the Tibetan Buddhist schools and the second largest after Geluk. The Nyingma school is based primarily on the teachings of Padmasambhava, who is revered by the Nyingma school as the "second Buddha." Padmascambhava's system of Vajrayana or Tantric Buddhism was synthesized by Longchenpa in the 14th century. The distinctive doctrine of the Nyingma school is Dzogchen ("great perfection"), also known as ati-yoga (extraordinary yoga). It also makes wide use of shamanistic practices and local divinities borrowed from the indigenous, pre-Buddhist Bon religion. Nyingma monks are not generally required to be celibate.
Kagyüpa ("Oral Transmission School"; also spelled Bka'-brgyud-pa) is the third largest school of Tibetan Buddhism. Its teachings were brought to Tibet by Marpa the Translator, an 11th century Tibetan householder who traveled to India to study under the master yogin Naropa and gather Buddhist scriptures. Marpa's most important student was Milarepa, to whom Marpa passed on his teachings only after subjecting him to trials of the utmost difficulty. In the 12th century, the physician Gampopa synthesized the teachings of Marpa and Milarepa into an independent school. As its name indicates, this school of Tibetan Buddhism places particular value on the transmission of teachings from teacher to disciple. It also stresses the more severe practices of hatha yoga. The central teaching is the "great seal" (mahamudra), which is a realization of emptiness, freedom from samsara and the inspearability of these two. The basic practice of mahamudra is "dwelling in peace," and it has thus been called the "Tibetan Zen." Also central to the Kagyupa schools are the Six Doctrines of Naropa (Naro Chödrug), which are meditation techniques that partially coincide with the teachings of the Tibetan Book of the Dead.
Sakyapa is the smallest of the four schools of Tibetan Buddhism. It is named for the Sakya ("Gray Earth") monastery in sourthern Tibet. The Sakya monastery was founded in 1073 by abbots from the Khön family. The abbots were devoted to the transmission of a cycle of Vajrayana teachings called "path and goal" (Lamdre), the systemization of Tantric teachings, and Buddhist logic. The Sakyapa school had great political influence in the 13th and 14th centuries.
Gelugpa (or Dge-lugs-pa or Gelukpa, "School of the Virtuous"), also called the Yellow Hats, is the youngest of the Tibetan schools, but is today the largest and the most important. It was founded in the late 14th century by Tsongkhapa, who "enforced strict monastic discipline, restored celibacy and the prohibition of alcohol and meat, established a higher standard of learning for monks, and, while continuing to respect the Vajrayana tradition of esotericism that was prevalent in Tibet, allowed Tantric and magical rites only in moderation." {1} Practices are centered on achieving concentration through meditation and arousing the bodhisattva within. Three large monasteries were quickly established near Lhasa: at Dga'ldan (Ganden) in 1409, 'Bras-spungs (Drepung) in 1416, and Se-ra in 1419. The abbots of the 'Bras-spungs monastery first received the title Dalai Lama in 1578. The Gelugpa school has held political leadership of Tibet since the Dalai Lamas were made heads of state by the Mongol leader Güüshi Khan in 1642.
