Social Functions and Institutionalization
As time progressed, the Stems and Branches system found widespread application in social functions and institutional processes, transforming from a primitive timekeeping tool into a comprehensive cultural system. During the Western Han Dynasty, philosopher Dong Zhongshu’s “Luxuriant Dew of the Spring and Autumn Annals” combined the stems, branches, and Five Elements theory with political ethics, formulating the “Resonance Between Heaven and Humanity” theory and imbuing the system with political and philosophical significance.
With the rise of metaphysical studies during the Wei and Jin dynasties, fate calculation based on the stems and branches became increasingly systematic. The compilation of fortune-telling texts like “The Comprehensive Book of Three Lives” and “The Ocean Depths of Fate Calculation” demonstrates that a rigorous system had formed. During the Ming and Qing dynasties, calendars such as “The Book of Coordinating Time and Determining Directions” and “Ten Thousand Year Calendar” became widely circulated, bringing this calendrical system into ordinary households. With imperial reign titles running parallel to stem-branch year designations, this system became a shared temporal coordinate system for both officials and commoners. From court sacrifices to weddings and funerals among common people, selecting auspicious days using this system became an essential cultural ritual, profoundly influencing practical life across all social strata.
Cross-Cultural Transmission
As a crucial component of Chinese civilization, the Stems and Branches system spread throughout East Asia through cultural exchange. Japan’s “Kojiki” and “Nihon Shoki” adopted this system for recording years; Korea’s “History of the Three Kingdoms” similarly used it to document history; and ancient Vietnamese documents also extensively applied the system. This cross-cultural transmission created a shared framework for temporal memory throughout the East Asian cultural sphere.
After the Tang Dynasty’s “Great Expansion Calendar” was introduced to Japan, Japanese calendars adopted the stems-branches year-marking method. In Vietnamese medical texts like the Nguyen Dynasty’s “Great Southern Materia Medica,” medicinal herb collection times were all indicated using the stems and branches. These cultural exchange artifacts demonstrate the system’s universality and cultural adaptability as a method of encoding time.
During Buddhism’s eastward spread, the challenge of converting between Buddhist and stems-branches calendars prompted ancient scholars to develop more precise year-counting methods. Buddhist texts like “The Sounds and Meanings of All Sutras” contain numerous comparative records of stems-branches and Indian calendrical systems, becoming important documents of dialogue between ancient civilizations.
The Basic Structure and Internal Logic
Structure and Connotations of the Twelve Earthly Branches
The Earthly Branches consist of twelve symbols: Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, and Hai. They alternate between yin and yang: Zi, Yin, Chen, Wu, Shen, and Xu are yang branches; Chou, Mao, Si, Wei, You, and Hai are yin branches. This arrangement precisely corresponds to the natural cycles of twelve two-hour periods in a day and twelve months in a year.
The Branches are associated with directions: Zi represents north, Wu south, Mao east, and You west. The remaining eight branches are distributed among the intermediate directions, forming a complete directional system. These directional correspondences aren’t abstract concepts but are based on observations of the sun’s trajectory in the Northern Hemisphere, giving them an astronomical foundation.
The twelve Branches are also assigned to the Five Elements: Yin and Mao belong to Wood, Si and Wu to Fire, Shen and You to Metal, Hai and Zi to Water, while Chen, Xu, Chou, and Wei all belong to Earth. This distribution of the Five Elements may seem uneven but actually reflects the ancient cosmic view that “the four seasons have regular transformations, and the Five Elements have fixed positions”—Earth occupies the center, with Earth’s characteristics present in all four seasons.