At the beginning of the eleventh century we hear of foreign monks arriving from various countries.  The chronicles[928] say that the chief workers in the new diffusion were La-chen, Lo-chen, the royal Lama Yeses Hod and Atisa.  The first appears to have been a Tibetan but the pupil of a teacher who had studied in Nepal.  Lo-chen was a Kashmiri and several other Kashmiri Lamas are mentioned as working in Tibet.  Yeses Hod was a king or chieftain of mNa-ris in western Tibet who is said to have been disgusted with the debased Tantrism which passed as Buddhism.  He therefore sent young Lamas to study in India and also invited thence learned monks.  The eminent Dharmapala, a monk of Magadha who was on a pilgrimage in Nepal, became his tutor.  Yeses Hod came to an unfortunate end.  He was taken captive by the Raja of Garlog, an enemy of Buddhism, and died in prison.  It is possible that this Raja was the ruler of Garhwal and a Mohammedan.  The political history of the period is far from clear, but evidently there were numerous Buddhist schools in Bengal, Kashmir and Nepal and numerous learned monks ready to take up their residence in Tibet.  This readiness has been explained as due to fear of the rising tide of Islam, but was more probably the result of the revival of Buddhism in Bengal during the eleventh century.  The most illustrious of these pandits was Atisa[929] (980-1053), a native of Bengal, who was ordained at Odontapuri and studied in Burma.[930] Subsequently he was appointed head of the monastery of Vikramasila and was induced to visit Tibet in 1038.[931] He remained there until his death fifteen years later; introduced a new calendar and inaugurated the second period of Tibetan Buddhism which is marked by the rise of successive sects described as reforms.  It may seem a jest to call the teaching of Atisa a reform, for he professed the Kalacakra, the latest and most corrupt form of Indian Buddhism, but it was doubtless superior in discipline and coherency to the native superstitions mixed with debased tantrism, which it replaced.

As in Japan during the eleventh and twelfth centuries many monasteries were founded and grew in importance, and what might have happened in Japan but for the somewhat unscrupulous prescience of Japanese statesmen actually did happen in Tibet.  Among the numerous contending chiefs none was pre-eminent:  the people were pugnacious but superstitious.  They were ready to build and respect when built the substantial structures required to house monastic communities during the rigorous winter.  Hence the monasteries became the largest and safest buildings in the land, possessing the double strength of walls and inviolability.  The most important was the Sakya monastery.  Its abbots were of royal blood and not celibate, and this dynasty of ecclesiastical statesmen practically ruled Tibet at a critical period in the history of eastern Asia and indeed of the world, namely, the conquests of Chinggiz[932] and the rise of the Mongol Empire.