Buddhism was eclipsed in Tibet during much of the tenth century and eventually had to be reintroduced from India.
This process of reintroduction is known as the “Later Diffusion of the Dharma.” Between the twelfth and fourteenth centuries, the Tibetan tradition crystallized into four major schools.
The Nyingma, or “Old,” School traced its origin to Padmasambhava. The Sakya School played an important role in Tibetan relations with the Mongols and in the formation of a Tibetan monastic state.
The Kagyu School produced Milarepa, one of Tibet’s most beloved saints. And the Geluk School produced the lineage of the Dalai Lamas, a lineage that has come to dominate the religious life of Tibet.