Early in the seventh century China moved into a new stage of its history. The Tang Dynasty (618-907) was a powerful and politically united regime that initially established order over the shifting and chaotic situation that had prevailed for more than 300 years in China.At the same time, the great Tibetan leader Songtsan Gambo brought together more than 10 separate tribes, an event commonly seen as marking the establishment of the Tubo Kingdom, making his capital in present-day Lhasa. Songtsan Gambo had good relations with the Tang court and benefitted from the importation of Tang technologies (advanced for the day), and was influenced by Tang culture and politics. He twice sent ministers to the Tang Dynasty court requesting a member of the imperial family be given him in marriage and in 641 he married Princess Wencheng, a member of Emperor Taizong's family. Introduced into Tibet during this time were Chinese technologies for wine-making, grinding, and paper and ink making. Sons of the Tibetan aristocracy were and ink making. Sons of the Tibetan aristocracy were sent to the Tang capital Chang'an (present-day Xi' an) to study. Literati from the Tang court went to the Tibetan capital to handle communications with the emperor. During the reign of Songtsan Gambo political, economic and cultural relations between Tang and Tubo were friendly. Laudatory titles given King Songtsan Gambo by Emperor Gaozong include Commandant-escort, Commandery Prince of the Western Sea and Com panion Prince.

This pattern of friendly relations established during the reign of Songtsan Gambo was carried on during the next two hundred years. In 710 the Tang Princess Jincheng was sent to Tibet to marry the Tubo King Tride Tsugtsen, accompanied by several tens of thousands of pieces of embroidered satin brocade, a variety of technical writings and various other useful items. Princess Jincheng later gave money to support Buddhist monks from Yutian (now in modern Xinjiang) and elsewhere on their trips to Tibet to build monasteries and translate sutras. She also requested that Chinese classical works such asThe Book of Songs With Annotation by Mao Heng, The Book of Rites, Zuo Qiuming's Chronicles, andXiao Tong's Literary Selectionsbe sent to her from the Tang court.

In 821 King Chiri Pachen of Tibet three times sent envoys to Chang' an to discuss forming an alliance with the Tang Empire. Emperor Muzong ordered his prime minister to effect the alliance in a grand ceremony held in the western suburbs of the capital. The following year high-ranking representatives of the Tang court including Liu Yuanding were dispatched to Tibet to participate in a similar ceremony marking the alliance held in the eastern suburbs of Lhasa. Representatives of the Tibetan king included his chief ministers.

This all occurred during the first and second years (822 and823) of the Changqing reign of the Tang Dynasty, and accordingly has been called the "Changqing Alliance" by historians. The two parties agreed to "amity as though they were of one family" and to "treat their sacrificial alters as though they were one." An account of the alliance is recorded on three tablets, and the "Tang- Tubo Alliance Tablet", one of the three, still stands before the Jokhang Monastery in Lhasa.

Beginning around 842 the Tubo Kingdom broke up. Rival groups of ministers and members of the royal family engaged in internecine struggle. Power was reduced to the local level. This state of affairs continued for more than 400 years.