Early jade was used as an ornament or sacrificial utensils. The earliest Chinese carved-jade object appeared in the Hemudu culture in the early Neolithic period (about 3500–2000 BCE). During the Shang dynasty (c. 1600–1046 bce), Bi (circular perforated jade) and Cong (square jade tube) appeared, which were guessed as sacrificial utensils, representing the sky and the earth. In the Zhou Dynasty (1046–256 bce), due to the using of higher hardness engraving tools, jades were carved more delicately and began to be used as a pendant or ornament in clothing. Jade was considered to be immortal and could protect the owner, so carved-jade objects were often buried with the deceased, such as a jade burial suit from the tomb of Liu Sheng, a prince of the Western Han Dynasty.