The Earthly Branches, also known as the Twelve Earthly Branches, Twelve Chens, or Twelve Zis, are part of the traditional Chinese calendar system of Heavenly Stems and Earthly Branches. These are the twelve symbols: Zi (子), Chou (丑), Yin (寅), Mao (卯), Chen (辰), Si (巳), Wu (午), Wei (未), Shen (申), You (酉), Xu (戌), and Hai (亥). The yin and yang attributes of the Earthly Branches are determined by the odd and even order of these twelve branches. The odd-numbered branches Zi, Yin, Chen, Wu, Shen, and Xu belong to yang branches, while the even-numbered branches Chou, Mao, Si, Wei, You, and Hai belong to yin branches. The Earthly Branches have four types of relationships: mutual generation, mutual restriction, mutual clash, and mutual combination. Each element of the Earthly Branches is a unity of matter (Five Elements), time, and space. Matter includes time and space, and it possesses cyclical relationships of mutual generation and restriction, as well as development through metabolism. The application of Earthly Branches began during the reign of the great Yao of the Xuanyuan period. The ancients used them not only as symbols for recording events but also to explain the waxing and waning of yin and yang energy throughout the year.

Zi represents the Rat, Chou represents the Ox, Yin represents the Tiger; Mao represents the Rabbit, Chen represents the Dragon, Si represents the Snake, Wu represents the Horse, Wei represents the Sheep, Shen represents the Monkey, You represents the Rooster, Xu represents the Dog, and Hai represents the Pig.