History of Tibetan Buddhism

Buddhists, predominantly from India, first actively disseminated their practices in Tibet from the 6th to the 9th centuries CE. During the Era of Fragmentation (9th–10th centuries), Buddhism waned in Tibet, only to rise again in the 11th century. With the Mongol invasion of Tibet (1240 onwards) and the establishment of the Mongol Yuan dynasty (1271–1368) in China, Tibetan Buddhism spread beyond Tibet to Mongolia and China.

Source: Wikipedia — History of Tibetan Buddhism (CC BY-SA 4.0)