In long summer, every household in the south of the Yangtze River eats black rice. This kind of black rice is oily and fragrant, and it is cooked by soaking glutinous rice in black leaves for a few hours. Eating in this way can dispel wind and detoxify, prevent mosquitoes from biting insects, and people believe that eating black rice in long summer will protect people's safety.

It is said that during the Warring States Period, Pang Juan and Sun Bin went into the mountains together to learn the art of war from Guiguzi. Pang Juan, eager for success, learned some superficial things and went down the mountain. Sun Bin was diligent and studious, and Guiguzi passed on the essence of the art of war to Sun Bin. When Pang Juan learned this, he was very jealous of him. He first gave Sun Bin a warm reception for a pretence, then crippled his leg, put him in jail and tricked him into writing the art of war. Sun Bin, in order to save himself, deliberately pretended to be crazy, and burned the written art books. Pang Juan suspected that Sun Bin was pretending to be crazy, so he dragged him into the pigsty. The old jailer had a good mind's eye. After consulting with his wife, he soaked glutinous rice in black leaves, cooked it and kneaded it into small dumplings for Sun Bin. Pang Juan thought Sun Bin was eating pig manure, so he relaxed his supervision. Soon after, Sun Bin was rescued by the Qi people, and Sun Bin made great achievements in Qi, defeating and killing Pang Juan. Sun Bin survived and avenged himself because of the black rice. Since then, every year on long summer Day, people also compete to eat black rice for asylum.