李渊
The existence of Tibet was unknown to the Chinese until 608, when Tibetan emissaries from Emperor Namri Songtsen arrived with tribute to Sui China. In 634, his son Songtsen Gampo sent tribute and a request for a "heqin" ("marital alliance"). In the interim, a North China aristocrat had defeated the Sui and declared himself Emperor Gaozu of Tang. 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.