Li Shimin
During Tang rule, it was the border with the Tibetan Empire. Emperor Songtsen Gampo of Tibet tried to invade Tang China through this gate. Emperor Taizong of Tang offered him Princess Wencheng at Songzhou (now Songpan) in 641. According to Tibetan and Chinese legends, Princess Wencheng then brings with her among other things the Jowo statue to the Tibetan Empire.