Si-wang-mu, who lived eternally in the Jade Mountains, was a Chinese mother goddess or Mother Queen of the West. She was a deputy of heaven who could see the world from her mountain peak and send punishments to evil doers. Si-wang-mu may have been the same goddess as Si-mu of the oracle bones. In the first century B.C., Si-Wang-Mu is paired with Dung-wang-fu, the father king of the East. During the second century A.D., Si-wang-mu was depicted with wings. She has also been depicted with serpent's tails for feet.
When the Emperor Mu requested that she give him the elixir of immortality, Si-wang-mu refused, but shared with him, instead, seven peaches which he planned to plant to obtain immortality. He then learned they bear fruit only once in 3000 years and not on earth.
Sources: "An Ancient Chinese Mystery Cult" Homer H. Dubs The Harvard Theological Review, Vol. 35, No. 4. (Oct., 1942), pp. 221-240.
"Outlaws' Dreams of Power and Position in Shuihu zhuan"
Chinese Literature: Essays, Articles, Reviews (CLEAR), Vol. 18. (Dec., 1996), pp. 45-67.
Alternate Spellings: Xi-wang-mu, Hsi wang mu, Si wang mu, Xi wang mu