Tibetan history begins in the 7th century. Tibetans broke in the area where they settled until present time and made a great chaos in that part of Asia. Their arriving was similar to Huns arriving to Europe. Their leader was King Songsten Gampo and he ruled Nepal and partly Yunnan. Soon after, they moved a little bit more on north and occupied the city of Kashar and the Silk Road. Anyway, Tibetan expansion lasted only until 842. High plateau became their home forever. Tibet accepted feudal system. It was a year of King Langdarma's death, so afterwards Tibet was ruled by Buddhist clergy. Tibet had accepted Buddhism as its main religion already in 3rd cenury. Tantric Buddhism was imported from India and in Tibet it was modified by adopting the authentic animistic religion of Tibet (called Bon). Buddhist clery became very powerful in Tibet and they started to fight within theirselves for political power monopoly. Monasteries were appearing all over the region. Yellow Hat sect (Gelugpa) were the most categorical to win, so they conquered theri rivals Sakyapa in 1641 with a help of the Buddhist Mongols. Since then, Dalai Lama became the Yellow Hats' and Tibetan leader. It's a title which Mongols gave to Tibetan ascedent. Dalaj Lama means 'Ocean of Wisdom'. When one Dalaj Lama died, monks searched for newborn child who could be considered as the reincarnation of the last. That's how Dalaj Lamas were elected. From 1911 to 1950, Tibet was independent coutry. It was a period of the last Qing Dynasty fall and Kuonmintag rule of China. In 1949, Mao Zedong proclaimed the People's Republic of China. Communists considered that Tibet is a part of this new Chinese state formation, so after short war, Tibet was within Chinese borders.
It's very hard to interpret Tibetan history after 1950. Chinese authorities claim that their communist regime brought modernisatin, economic and transporting development (2006 was opened railway line between Lhasa and rest of China) and liberation from feudal serfdom. On the other hand, many Tibetans were killed, executed or imprisoned during these last 50 years, particulrly during the Great Leap Forward and Cultural Revolution. Those events were marked by 'cultural genocide'. Dalaj Lama has been in excile since 1960 , but he is still considered as a leader of 100, 000 Tibetans. He is very popular in the Western World and in 1989 he won the Nobel peace prize. As China became world's ecomomic force, other main countries decreased a pressure on China to allow Tibetan independence. Dalaj Lama is now fighting for Tibet to be autonomus region of China, almost giving up of its independence. It's hard to be realistic when thinking about relation between China and Tibet. You have probably watch an excellent film '7 years in Tibet' with Brad Pitt. There is a picture of pre-50 Tibet as an idyllic place of peace, tradition, belief and honesty, as a rea 'Shangri-La'. Tibet was also a place of slavery and great poverty with autocratic regime. Chinese communist regime made a lot of mistakes in its history, but all China, not only Tibet, suffered from them. China invested a lot in Tibetan economy and its tourist industry too. China also has a very good laws to protect their national minorities, religions, customs and traditions. It seems like Chinese really realized that their diversity is a very significant elemnt of their nation's beauty. Lately, thanks to political programm called 'Develop the West', many Hans migrated to Tibet. Domicil inhabitans consider it as a new threat to Tibetan culture and heritage. Maybe it's still heavy to say that. Tibet occupies very large area and has only 2,7 million people. Some other parts of China have an opposite problem, so many of these migrants are there in searching for better life-oportunity.