A mural in Jokhang Temple in Lhasa, the capital city of southwest China's Xizang Autonomous Region, vividly portrays Princess Wencheng's arrival in the Tibetan region about 1,400 years ago. According to historical records, the Tang Dynasty (618-907) princess departed from Chang'an, now known as Xi'an, and overcame myriad obstacles en route to the west. Legend has it the "sun-and-moon mirror" she carried slipped from her grasp, its fragments landing on two hills. Thus, they were named Riyue Mountain, or Sun-and-Moon Mountain. The mountain lies where the Loess Plateau meets the Qinghai-Xizang Plateau. It also marks the boundary between China's agricultural and nomadic civilizations.