The institution of decorating coffins was a part of funeral ritual in the pre-Qin period and featured strict hierarchy. One of its versions was the practice of decorating coffins with bi discs. Jade bi as funeral objects are often seen in Chu State tombs, and many of them are placed outside coffins,which, however, remains beyond researchers' attention as the coffins have been rotted or robbed in most cases. In Chu Tomb No. 2 at Baoshan, the coffin-furnishing institution and the exact place of jade bi are seen rather clear. The finds indicate that the jade bi must have been fixed as coffin decorations outside the inner coffin, on the end wall. It is very likely that they were intended to function as the opening for the spirits of the deceased to pass through. The use of bi as funeral objects can be traced to the Hongshan and Liangzhu cultures, and was followed in the Han period. But the institution of decorating coffins with bi in the Han dynasty paled before the previous one in both function and religious sense. On the one hand, the bi for coffin decoration were largely not real and were transformed towards a design; on the other, the number of bi and the place where they were fixed were decided extremely at will.
