Indo-Tibetan Buddhism by David L. Snellgrove

With the rise of the Mongol Empire in the 13th century, Tibetan Buddhism began to spread in Central Asia and China. The process resumed with the second or “latter” transmission ( phyi dar) of Buddhism to Tibet, which resulted in the formation of the “New” ( gsar ma) schools of Tibetan Buddhism, the Geluk, Kadam, Kagyü, Jonang, and Sakya traditions. The “Ancient” Nyingma ( rnying ma) school of Buddhism also claims that its secret Tantric teachings were also transmitted to Tibet at this time. This first transmission constitutes the basis of all of the Tibetan Buddhist traditions, as a number of exoteric Buddhist works such as sutras were translated into Tibetan at this time. The first transmission of Buddhism to Tibet took place with the support of the imperial government, and it continued until disrupted in the mid-9th century by the collapse of the Tibetan empire. Tibet continued to receive transmissions of texts and practices from India until approximately 1500 CE, and thus received the full flowering of Indian Buddhism, particularly the tantric or Vajrayāna form of Buddhism that developed in India around the 7th century. Buddhism reached Tibet relatively late, around the 7th century, and within a few centuries it became the dominant religion on the Tibetan plateau.

Indo-Tibetan Buddhism by David L. Snellgrove