It is the Ten Heavenly Stems. The words of Heavenly Stems come from the ancients’ summary of the laws of all things. The details are as follows:
A, all things A are born (born)
B, All things Yi grow (grow)
C, all things Bingran (brilliant)
Ding, all things Ding Zhuang (strong)
W, all things Wu Sheng (luxuriant) )
Ji, all things are bent (bent)
Geng, all things are replaced (replaced)
Xin, all things are hard (hardship)
Ren, all things are heavy (responsibility is heavy)
Gui, all things are dead (death)
Stem and branch calendar
Stem and branch calendar is composed of heavenly stems and earthly branches* **The chronology of 60 stems and branches (see the table in the sequence list above for details) (or see the five elements and zodiac signs below), and in this way, 60 years is a cycle.
The first year of a cycle of stems and branches is "Jia Zi", the second year is "Yi Chou", and so on, a cycle of 60 years; a cycle is reused after it is completed, and the cycle begins again and again. (60 is the least common multiple of 10 and 12, so every 60 years is a cycle).
For example, 1644 was probably the year of Jiashen, 1704 60 years later was also the year of Jiashen, and 1944 300 years later was still the year of Jiashen. Note that the above is only a rough correspondence, because the Gregorian calendar and the Ganzhi calendar are different calendars, and the starting points of the years are different.
Reference for the above content: Baidu Encyclopedia—Heavenly Stems and Earthly Branches, Baidu Encyclopedia—Heavenly Stems