The Changzhu Monastery is located on the eastern bank of the Yalong River in the district of Shannan. It is famous primarily for the legend of how it got its name. It is said that once upon a time, the site of the monastery was an extremely deep lake. In the lake, there was a five-headed dragon. After Songtsen Gampo gained control of Tibet, he decided to drain the lake and build a castle in its place. To that end, he invited two masters to lure a big bird to attack the dragon. First, the masters imitated the sound of the bird and lured the dragon out. Then, they imitated the sound of the dragon to get the bird to come. At that point, the dragon and the bird started a fight. At last, the bird chopped off two of the dragon's heads with its wings. Seven days later, the lake disappeared. To mark this success, some pearls were buried as the cornerstone for the monastery, which is how the monastery got its name.