Tripod, was first used to cook food in ancient times, in ancient pottery has already had "pottery tripod". Tripod is also the main rites in ancient times, is the nobility of all levels of special supplies. Ding is also a symbol of social political and economic power in ancient times. The majesty of the cauldron comes from "Yu the Great casting the Nine Cauldrons", which is a symbol of the unification of the world and the establishment of the central government.