 1723 account by the French Jesuits Dominique Parrenin, there was a well in Dong'e which was normally kept closed and sealed, and which was only opened when water was taken to be used in preparation of "ejiao" for the emperor's court.According to Parennin, the product was traditionally prepared during the late fall and winter (from after the harvest and until the beginning of March).It was supposed to be made from the skin of a recently killed well-nourished black donkey.