子(zǐ), Chou(chǒu), Yin(yín), Mao(mǎo), Chen(chén), Si(sì), Wu(wǔ), Wei(wèi), Shen(shēn) ), unitary (yǒu), Xu (xū), and Hai (hài). Also called twelve branches. In ancient China, the twelve earthly branches were used to track time and months. The earthly branch time is to divide a day into 12 periods, which are represented by the twelve earthly branches. Zi hour is from 23 to 1 o'clock, Chou hour is from 1 to 3 o'clock, etc., which are called twelve hours. According to the earthly branch calendar, the month in which the winter solstice occurs is called the Zi month, the next month is called the Chou month, and so on. The earthly branches match the order of the ten heavenly stems, forming Jiazi, Yichou... Guihai, with a sixty-year cycle used to record days and years.