Guarding the palace sand is a method to judge whether a woman is "chaste" in ancient Chinese legends. Legend has it that the "Gong Wei" (that is, the gecko) who feeds cinnabar will never fall off after being pounded on a woman's limbs, but it will automatically fall off during sexual intercourse, so it is a floating cloud.

In ancient times, it was common to point a bright red mole on a girl's arm like Bai Lianhua to verify women's chastity, which was called "palace sand". People who don't understand think that "guarding the palace" means guarding the beauty of the sacred side.

Introduction.

The record of guarding the palace sand has existed in the literature of Qin and Han dynasties, and alchemists often find it in fairy tales, and later it was written into the medical code, but the specific statement is not the same. During the Sui and Tang Dynasties, Tang Materia Medica once questioned the scientific nature of guarding palace sand, but for various reasons, the consciousness of ordinary literati was enhanced. Since the Song and Ming Dynasties, guarding the palace sand has had a far-reaching influence on the folk culture and literary creation of later generations.