Haishi Day (or Cold Food Day) has its roots in both legend and tradition. The legend says there was once a brave and loyal subject of the Prince of Jin. This man, Jie Zhi Tui, cut off flesh from his thigh and offered it to the prince in a time when food was scarce. Jie then fled into the mountains with his mother to hide. To bring them out of hiding the Prince set fire to the mountains, hoping to scare them back to town. Instead Jie and his mother were found dead. This led to the Haishi day tradition of burning no fire and eating cold food.
The holiday may have roots based more in the tradition of keeping a fire going throughout each season. Since fire starting wood changes with each season, an ancient practice to light a new fire when winter became spring, spring became summer, summer became winter and winter turned into fall.

A Korean grave-side visitation ceremony, complete with cold food picnic.

Activities during the Cold Food Festival includes the visiting family graves tombs, cock-fighting, playing on swings, beating out blankets (to freshen them), tug-of-war. It is celebrated in various ways in Vietnam and Korea.