China and Tibet share 1500 years long history of a struggling relationship that started right after the first interaction among them with the marriage of Chinese princess Wencheng to King Songtsan Gampo of Tibet. It marked the beginning of Tibetan Buddhism and expansion of the Tibetan empire in 640 AD.
But 692 saw a change in power as the defeated Tibetan king befriended the eastern Turks and Arabs against the victorious Chinese who took back their western lands from Tibetan’s hold. The Chinese ruled with power for some time expanding their grasp over Central Asia before facing defeat in the Battle of Talas River in the mid eighth century that shifted the control of the area back over to Tibet.
Tibet then extended its land holdings by adding present day Xian and most of northern India to it in 763. These struggles were pacified for a time after both neighbors signed a peace treaty in 821-22.
By the thirteenth century, the Tibetans gained even more real estate in Mongolian lands thanks to their allegiance with Genghis Khan. The relations between Tibet and Mongolia strengthened when the daughter of ruler Kublai Khan was married to a Tibetan Sakya descendant. The ties also grew from a mere political to spiritual level with the sharing of Tibetan Buddhist believes from Drogon Chogyal Phagpa to the Mongolian emperor.
A renewed struggle between Tibet and China started with the fall of Mongolian empire to Han China in 1368. The coming years saw great agitations for political power resulting in the Qing, the final Chinese imperial dynasty, which also acknowledged Dalai Lama as the spiritual authority in its later years. The current atheist Chinese government however could care less about their historical relationship and has stolen all of Tibet’s sovereign land, leaving the Tibetan government exiled. A large number of Tibetans, including the Dali Lama, But, the struggle of Tibet to assert its independence still continues.