Sichuan was the seat of ancient China's silk-worm rearing region. It was inhabited by diverse tribes, with no central government. Because of this lack of unity, it was not uncommon for inter-tribal disputes to arise and result in warfare. In this region lived a beautiful girl, whose father had gone off to battle, and not returned for over a year. The girl, being very close to her father, pined away for him, and became gravely ill. Fearing she would lose her daughter as well, the mother declared that anyone who brought her husband home would have her daughter's hand in marriage. Many young men tried, but failed. Then one day, the father's horse broke free of his rope and galloped off. Two days later, he returned, with his master on his back. People were amazed, because the horse had obviously gone off in search of the man. They declared that, surely, the horse possessed a soul.

As a reward, the man gave his horse extra fodder and treats. However, the horse would touch none of it, and each time the daughter came near, he would rear his body and whinny. Mystified, the father asked his daughter what was going on, and reluctantly, she told him of her mother's promise. "Who would betroth their daughter to a beast?!" roared the father. At these angry words, the horse began to kick and bellow in his stall. In a rage, the man killed the horse and buried him beneath the mulberry tree.

One day, the girl was walking past the tree. The spirit of the horse rose up from its grave and enveloped her, whisking her off into the skies. For two days, the father searched in vain for his daughter. Then he noticed a curious object hanging from the mulberry branch. On closer inspection, he saw it was a silken coccoon, and inside it was his daughter, transformed into a silkworm. From that day onwards, people would see the girl riding across the land on horseback. She would stop and teach them how to raise sillkworms and cultivate mulberry trees, on which leaves the silkworms fed. When asked, she said, "The gods have conferred this task upon me, so I may never forget what it is to be just." She came to be known to all as Cannu, the Silkworm Girl.