As far back as the Chou Dynasty (1027-402 B.C.) it has been believed that a person has two souls. The p’o, which first enters into a human during the development of the fetus, was characterized by yin and was associated with a person’s material aspect. Normally the p’o descended into the underworld, or the Yellow Springs. However, if a person had a very powerful p’o or if a deceased body was exposed to either sunlight or moonlight, it could cause the p’o to remain, animate the body, creating a REVENANT, and use it to fulfill its own needs. When this happens, a vampiric being known as a CH’ING SHIH is created.

Source: Heinze, Tham Khwan, 37-40; Kuhn, Soulstealers, 96-97; Watson, Death Ritual, 8-9, 56, 193; Werne, China of the Chinese, 231-233