What is the Dantian 丹田？

"Dantian" was originally a term used by the Taoist internal alchemy school for cultivating essence (jing), qi (vital energy), and spirit (shen), and is now widely adopted by various qigong traditions. Citing the Xianjing (Classic of Immortals), the Dongyi Baojian (Treasure Mirror of Eastern Medicine) not only identifies the locations of the dantians but also expounds their functions: "The brain is the sea of marrow, serving as the upper dantian; the heart is the crimson fire, the middle dantian; three inches below the navel is the lower dantian. The lower dantian is the repository of essence, the middle dantian the repository of qi, and the upper dantian the repository of spirit."

Ancient Chinese referred to essence, qi, and spirit as the "Three Treasures," regarding the dantians as their storage sites. Thus, they attached great importance to the dantians, viewing them as the "foundation of life and nature."