the cold food festival is first mentioned in huan tan's "new discussions", composed around the beginning of the 1st century. it records that the commoners of taiyuan commandery avoided using fire in preparing their food for five days around midwinter, upholding this taboo even when they are gravely ill. this was done in jie zhitui's honor. a biography in the "book of the later han" relates how the magistrate for bingzhou (i.e., taiyuan) found people rich and poor observing a "dragon taboo" against lighting a fire during the month of jie's death in midwinter, lest they anger his spirit. many of the old and young died every year because of the hardship this brought. the magistrate zhou ju wrote an oration around 130 praising jie but admonishing the people for a tradition that harmed so many that it could not have been what the sage intended. he then had the oration displayed at jie's temple and distributed among the poor. this did not end the cold food festival, but the biography notes that local superstitions did improve "to a certain extent". the improvement is not explained but, at some point over the next century, it moved from the middle of winter to late spring, 105 days after the dongzhi solar term. since it also spread from taiyuan to the surrounding commanderies of shangdang, xihe, and yanmen and was still causing some hardship, cao cao attempted to outlaw the cold food festival in 206. the heads of offending families were liable for 6 months' hard labor, their local official was liable for one month himself, and their magistrate was to lose one month's salary. cao cao's effort was a failure, with observance of the cold food festival on qingming and for up to a month around it being reported by the mid-3rd century. shi le, the jie emperor of the later zhao in the early 4th century, again tried to forbid it. the next year a massive hailstorm devastated crops and forests throughout shanxi. on the advice of his ministers, he again approved the festival in the region around taiyuan. the northern wei similarly banned the festival in 478 and 496, but were also compelled to approve its observance around . these prohibitions failed to such an extent that, by the time of jia sixie's "qimin yaoshu", a day-long cold food festival had spread across most of china, moved to the day before the qingming solar term.