Heavenly Stems&Earthly Branches
Because treachery had taken root and demons and monsters had appeared, the rebellion of Chi You arose in the age of the Yellow Emperor. Grieved by the tribulations of the people, the Yellow Emperor went forth to do battle with Chi You in the wilds of Zhuolu. Yet although the bloodshed stretched for a hundred li, he could not subdue him. It was at this time that the Yellow Emperor set about forging weapons — swords, shields, and halberds.
Fasting and purifying himself, the Yellow Emperor raised an altar and, on the day of the summer solstice, offered sacrifice to Heaven and Earth. Heaven, moved by his sincerity, sent down the Ten Heavenly Stems, which signify Heaven — namely Jia, Yi, Bing, Ding, Wu, Ji, Geng, Xin, Ren, and Gui — and likewise the Twelve Earthly Branches, which signify Earth — namely Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, and Hai. The Yellow Emperor arranged the Ten Heavenly Stems in a circle to mirror the round form of Heaven, and the Twelve Earthly Branches in a square to mirror the square form of Earth. From this, the Heavenly Stems came to stand for Heaven and the Earthly Branches for Earth; once the two were joined, each fulfilling its proper function, they could be employed to bring order to the realm. Such was the origin of the Ten Heavenly Stems and the Twelve Earthly Branches.
Later, Da Nao feared that future generations would be beset by the same affliction. “Alas!” he said. “The Yellow Emperor was a sage, and even he could not subdue and punish the wicked. Should the people once again meet with calamity and hardship, what recourse would they have?” He therefore paired the Ten Heavenly Stems with the Twelve Earthly Branches, one by one, to form the sexagenary cycle (六十甲子).
天干的顺序是：甲→乙→丙→丁→戊→己→庚→辛→壬→癸。
The order of the Heavenly Stems is: Jia → Yi → Bing → Ding → Wu → Ji → Geng → Xin → Ren → Gui.
天干的阴阳属性是：“甲、丙、戊、庚、壬”属阳，“乙、丁、己、辛、癸”属阴。
As to their yin–yang nature: Jia, Bing, Wu, Geng, and Ren are yang, while Yi, Ding, Ji, Xin, and Gui are yin.
