 The original names, value and functions of these objects have invited much speculation.The Zhou Li, itself probably compiled in the Han Dynasty, ascribes the circular "bi" as representing the heavens, the "cong" as representing the earth, the "gui" the east, the "zhang" the south, the "hu" the west and the "huang" the north.Although over two millennia old these names and symbolism were given to these objects by much later writers, who interpreted the objects in a way that reflected their own understanding of the cosmos.