the cold food or hanshi festival is a traditional chinese holiday which developed from the local commemoration of the death of the jin nobleman jie zitui in the 7thcentury under the zhou dynasty, into an occasion across east asia for the commemoration and veneration of ancestors by the 7th-century tang dynasty. its name derives from the tradition of avoiding the lighting of any kind of fire, even for the preparation of food. this practice originally occurred at midwinter for as long as a month, but the hardship this involved led to repeated attempts to ban its observance out of concern for its practitioners. by the end of the three kingdoms period (3rd century), it was limited to three days in the spring around the qingming solar term. under the tang, ancestral observance was limited to the single day which is now celebrated as the tomb-sweeping festival. the cold food festival is not an official holiday in any country or region, but it continues to see some observance in china, south korea, and vietnam.