In 634, King Songtsen Gampo sent an envoy to Luoyang, the Tang capital. When Songtsen heard that both the Turks and Tuyuhun hand marriage alliances with the Tang, he sent an envoy to the Tang capital to make a marriage proposal. The Tang turned it down and the Tibetan envoy told Songtsen that initially the Tang had accepted but the Tuyuhun were responsible for changing their decision. Songtsen attacked the Tuyuhun and the Dangxiang. Following his attack on the Tuyuhun, Songtsen stationed large n