Two dozen intelligent boys were sent by Songsten Gampo, ( the first emperor of Tibet to unite Tibetan plateau which include Qinghai) ro India to study Sanskrit literature and grammar. All except Thumi Sambhota died due to tropical diseases, banditry etc. Thumi Sambhota return and composed Tibetan alphabet and two grammar text which is still used to study Tibetan literature. Motive behind the creation of text was for adminstration of vast country spanning over 2.5 million square kilometer of land. The serious study and propagation of Buddhism came much later say about 100 years or 3 or 4 generation.