Scientists believe now that the earliest traces of neidan practices for women were found in the works of Xue Daoguang’s (1078?-1191) in his commentary to the Wuzhen pian, and the texts on sexual techniques fángzhōng shū 房中書 could be the earliest source too. Xue Daoguang came from the Nang realm, which is known as Nangzhong, Sichuan province, hence the picture of an ancient town above.
Monica Esposito, Encyclopedia Of Taoism, explains the difference: “Moreover, while the White Tiger, as a male or igneous Water, resides in a man’s testicles, the Red Dragon, as a feminine or aqueous Fire, resides in a woman’s breasts. This explains why a man and a woman begin their practices from exactly opposite Cinnabar Fields (dāntián 丹田). A woman must first concentrate on the Brook of Milk (rŭxī 乳溪) in the center of her chest (also known as qìxué 氣穴 or Cavity of Pneuma), and gently massage her breast to activate the circulation of blood and qi. The breasts are regarded as the receptacle of pure secretions that can enrich her natural endowment of qi.”
The path of practicing neidan is extremely difficult to follow (no matter what gender you are) due to complex texts and rare teachers, but it cannot stop me thinking about smart and beautiful women of modern times. My guess is that one philosophical ancient text, Nèiyè 內業 (Inner Cultivation) for example, some dăoyĭn 導引 gymnastic exercises and many, many sexual guides (fángzhōng shū 房中書) for everybody, probably could solve the most of health problems and give opportunity to live your own life in the same time. That is the guess only.