The stem and branch chronology is an ancient Chinese chronology. That is, according to the twelve earthly branches of A, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, Gui and Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai. Combine them in order to record the year. For example, Jiazi, Yichou, etc. returned to Jiazi after sixty years. The cycle starts over and over again. Our country’s traditional chronological system still uses the stems and branches to chronologically.