as chong er became king, he rewarded many people but he forgot jie zitui. he did not realize it until was reminded. however his invitation was refused and he flared up. soldiers were ordered to burn up the mountain to force jie to come out. finally they found jie and his mother scorched under a willow. he would rather die than yield to the power. chong er was so overwhelmed with regret that he ordered people hold memorial ceremony for jie. so every year on that day folks mourned for him and the day before ate cold meals, which avoided making fire. later the custom of inserting willow branches on gates was also added.