Handwritten Cantonese opera Sheet Music, stamped by 曲艺苑 the Performance and Art Center.

Broken Bridge is Act I of the play Legend of the White Snake.Lü Dongbin, one of the Eight Immortals, disguises himself as a man selling tangyuan at the Broken Bridge (斷橋) near the West Lake in Hangzhou. A boy called Xu Xian (simplified Chinese: 许仙; traditional Chinese: 許仙; pinyin: Xǔ Xiān; Jyutping: Heoi2 Sin1) buys some tangyuan from Lü Dongbin without knowing that they are actually immortality pills. He does not feel hungry for the next three days after eating them, so he goes back to ask why. Lü Dongbin laughs and carries Xu Xian to the bridge, where he flips him upside down and causes him to vomit the tangyuan into the lake.

In the lake, there is a white snake spirit who has been practising Taoist magical arts in the hope of becoming an immortal after centuries of training and cultivation. She eats the pills and gains 500 years' worth of magical powers. She therefore feels grateful to Xu Xian and their fates become intertwined. There is another terrapin (or tortoise) spirit also training in the lake who did not manage to consume any of the pills; he is very jealous of the white snake. One day, the white snake sees a beggar on the bridge who has caught a green snake and wants to dig out the snake's gall and sell it. The white snake transforms into a woman and buys the green snake from the beggar, thus saving the green snake's life. The green snake is grateful to the white snake and she regards the white snake as an elder sister.

Source: https://en.wikipedia.org/wiki/Legend_of_the_White_Snake