Princess Wencheng (Tibetan: Mung-chang Kungco, Chinese: 文成公主, pinyin: Wénchéng Gōngzhǔ) (died 680^[1]) was a niece of the powerful Emperor Taizong of China's Tang Dynasty, who left China in 640, according to records, arriving the next year in Tibet to marry the thirty-seven year old Songtsän Gampo (605?–650 CE) the thirty-third king of the Yarlung Dynasty of Tibet, in a marriage of state as part of a peace treaty along with large quantities of gold. She is popularly known in Tibet as Gyasa, or 'Chinese wife'.^[2] The princess is portrayed as a Buddhist and, along with Songtsän Gampo's Nepalese wife, Bhrikuti Devi, is said to have introduced Buddhism to Tibet.^[3]

The Chinese records mention receiving an envoy in 634 from Songtsän Gampo wherein the king requested (Tibetan sources say demanded)^[4][5] to marry a Chinese princess and was refused. In 635/636 the Tibetan king's forces attacked and defeated the 'A zha people (Chinese: Tüyühün), who lived around Lake Koko Nor in present-day Qinghai, along an important trade route into China. After a campaign against China in 635–6 (OTA l. 607) (during which Chinese won) the Chinese emperor agreed (under threat of force, according to Tibetan histories)^[4] to marry a Chinese princess to king Songtsän Gampo as part of the diplomatic settlement. As a marriage of state, the union must be considered a success as peace between China and Tibet prevailed for the remainder of Songtsen Gampo's reign.