The mountain was known as Chiling Range in ancient China. Legend has it that in the Tang Dynasty, Emperor Taizong granted Princess Wencheng a mirror named the Sun and the Moon before she married King Songtsen Gampo of Tibet. The mirror was said to see Chang'an, then capital, and her relatives. When she passed through Chiling Range, the princess threw the Sun and the Moon onto the mountain. Hence the name. To commemorate Princess Wencheng, the local people built two pavilions named the Sun and the Moon respectively. At the northwestern foot of the mountain a river runs westward. Hence its name. It is said that the river water was tears of Princess Wencheng who suffered from homesick. Worried that someday the river would have reached Chang'an if it run eastward, the princess prayed for turning its flow back. God was deeply moved and changed the flow of the river.