Earthly branches, which are also the characters used by the Chinese nation to record time, are called twelve earthly branches. "Ganzhi" was called "Sui" in ancient times, and the period of "Sui" was sixty jiazi (chronology of Ganzhi). The Book of Changes was written in 2000. Biography of Huang San: "King Mudd of Heaven, taken at the age of".
Tai sui is trapped in Ziyue, red in ugliness, holding up, Khan in Maoyue, promising, desolate in Siyue, hiding in the afternoon, no discussion, worse than Youyue, Mao Yan in, greater than Haiyue. Heavenly stems and earthly branches constitutes the traditional calendar year in ancient China. In ancient China, it was matched with heavenly stems to indicate the order of year, month and time.
In the ancient imperial era, there was the embryonic form of Ganzhi calendar and Nian. Wan Minying, a famous historian in Ming Dynasty, confirmed that the drought calendar was invented in the era of Emperor Wu of Han Dynasty according to the records of ancient documents in China, and it was recorded in detail in his book "Three Boys' Meeting".
Heavenly stems and earthly branches's invention had a far-reaching impact, and it was used in calendar, arithmetic, calculation, naming, etc. (Zi Tongzhijian, the official history compiled in the Northern Song Dynasty, used this set of official terms to record the years).