Buddhism was introduced into Tibet in the 7th century AD (the reign of Tubo King Songtsan Gambo), and gradually infiltrated Tibet's history, politics, economics, culture, exchanges and habits and customs to become the most extensively worshipped religion of Tibetans. Tibetan Buddhism (Lamaism) has exerted extensive and profound influence on the Tibetan race. Prolonged ethnic cultural exchanges also enabled Tibetan Buddhism to make its way into the Mongolian and other ethnic minority nationalities throughout China. Buddhism has long been widely worshipped in Tibet, the traditional Kham and Amdo areas. It has also made its way into Sikkim, Bhuttan, Nepal and Mongolia.
The spread of Buddhism to Tibet contributed to Songtsan Gambo, the Tibetan King lived in the 7th century AD. He did his best to establish friendly ties with neighboring countries and learned from the cultures of the other countries. His marriage with Princess Khridzun of Nepal and Princess Wencheng of China's Tang Dynasty (618-907) facilitated the introduction of Buddhism to Tibet. Each princess journeyed to Tibet with statues of Buddha and Buddhism scriptures. Artisans accompanying the princess were involved in the construction of Jokhang and Ramoge monasteries. And also Buddhist monks from Nepal and China began translating Buddhist scriptures. Buddhism thus turned to be spread in Tibet.
Tibet went though power struggle for more than half a century after the death of Songtsan Gambo. Buddhism failed to flourish until Tride Zhotsan, great grandson of Songtsan Gambo who took power in 710 AD. He married Princess Jincheng of the Tang Dynasty. The new bride moved the statue of Buddha, which Princess Wencheng brought to Tibet, to the Jokhang Monastery. Meanwhile, she arranged monks accompanying her to the Tubo Kingdom to take in charge of the monastery and related religious activities. She engaged in a painstaking effort and finally succeeding in persuading the Tubo court to accept monks fleeing from Western Regions and build seven monasteries to house them. While the measures further boosted the development of Buddhism in Tibet, they nonetheless sparked discontent amongst ministers worshipping the Bon religion. The ministers left no stone unturned to obstruct the development of Buddhism, with to situation lasting until Trisong Detsan, the son of Tride Zhotsan, came to power.
Trison Detsan relied on Buddhism to fight ministers who rallied behind the Bon religion. As part of the effort, he invited Zhibatsho and Padmasambhava, famous Indian monks, to build the Samye Monastery in 799 AD. Seven noble children were later tonsured to the monastery, which became the first monastery in Tibetan Buddhist history to tonsure monks. The event thus pioneered the tonsure system of Tibetan Buddhism.
In addition to inviting Indian monks to Tibet, Trisong Destan sent trusted emissaries to China's hinterland to invite monks to lecture in Tibet. Mahayana became one of the many Han monks who contributed to ensuring that Han Buddhism flourished in Tibet. Mahayana remained in Tibet for 11 years lecturing on Buddhism and completing nine books on Buddhist tenets.
Tubo kings in ensuing dynasties did their utmost to promote Buddhism by building monasteries and commissioning the translation of Buddhist sutras. At the same time, they granted monks royal incomes and even encouraged them to become involved in government affairs in order to undermine ministers who supported the Bon religion. The policy spawned the deep hatred of said ministers, who eventually arranged for the assassination of Tritso Detsan in 842 AD. The ministers threw their support behind Darma, the brother of Tritso Detsan, to become the new Tubo king. This was in turn followed by the large-scale suppression of Buddhism in the region.
Shortly after assuming power, Darma set out to suppress Buddhism, but was soon assassinated by Tibetan Buddhists, and war erupted between the different power factions. Slaves, who were thrown into the abyss of misery, rose to revolt. Tibet was torn apart by various forces. The "diffusion of Buddhism'' was thus halted.
The early 10th century witnessed the entry of a feudal society in Tibet, with each of the Tubo ministers occupying a part of the kingdom and becoming feudal powers in their respective localities. They proceeded to promote Buddhism in order to strengthen their own rule. Buddhism was thus revived in Tibet. In terms of form and content, however, Buddhism rising in Tibet during tit particular period was worlds apart from Tubo Buddhism. The 300-odd years of struggle between Buddhism and the Bon religion resulted in each absorbing the strong points of the other. Buddhism became increasingly localized as the region entered the feudal stage. Tibetan Buddhism emerged and entered a stage of rapid development.