The Mongol conquest in 1247 led to the installation of a religious leader, the Saskya Lama, as the viceroy of Tibet.
In the 15th century a reform Buddhist group, the Dge-lugs-pa (Yello Hat), gained power; in 1578 the head of this order was given the title of Dalai Lama by the great Mongol leader Altan Khan. With the help of the Mongols, the Dge-lugs-pa became the supreme rulers of Tibet
The Tibetan War
The Peoples Republic of China reconquered Tibet undermining the authority of the Dalai Lama, who, after a popular uprising, had to flee into exile in India.