The peace held for the remainder of the reigns of Taizong and Songtsen Gampo, although Tibet would pose major military threats for most of the rest of the Tang period.
When Songtsen Gampo's marriage overture arrived, Taizong, the second Tang emperor, was battling the Tuyuhun and did not initially respond, but did send the emissary Feng Dexia (馮德遐) to Tibet to establish peaceful relations.
Songtsen Gampo, believing the report, attacked Tuyuhun in late 637 and early 638, capturing some of them and forcing the rest to flee north of Qinghai Lake.
In fall 640, Songtsen Gampo sent his prime minister Gar Tongtsen Yülsung (aka Lu Dongzan, 祿東贊) to Tang to offer tributes of gold and jewels, again requesting marriage.
In response, Taizong created[clarification needed] a daughter of a kinsman, Princess Wencheng, preparing to give her to Songtsen Gampo in marriage.
[citation needed] In spring 641, Taizong sent his cousin, Li Daozong, Prince of Jiangxia, to accompany Gar Tongtsen Yülsung back to Tibet and to escort Wencheng.
[6][b] In 647, for when Taizong sent a force under the command of the Göktürk prince Ashina Shö-eul on a punitive expedition against the state of Kucha under its new king Hari Pushpa,[c] after his predecessor had refused to pay tribute in protest at China's interventionist policy,[10] Tibetan troops were requisitioned.
[citation needed] Moreover, in 648, when the Tang emissary Wang Xuance became stuck in political turmoil of an Indian state, he sought aid from both Tibet and Nepal and was assisted by both in defeating one of the factions in 649.
[12] With the weakening of Chinese power consequent on the An Lushan Rebellion (755–763), the Tibetans managed to recapture vast swathes of their lost territory, overrunning Songzhou and the surrounding area in 763, and even briefly capturing the capital Chang'an.
It was a decisive factor in the rerouting of China's silk commerce and East-West trade patterns, which shifted northwards through Uighur lands.