There are 10 Stems and 12 Branches in Chinese astrology calendar. The Stem and the Branch are used together. The Stem is used in front of (on top of) the Branch. They are combined into a cycle of 60 counting systems for Year, Month, Day and Hour cycles. The counting system begins from Wooden Rat and end with Water Pig. Chinese Birth Chart is built using this Stem-Branch calendar.
No one knows who invented the Stem-Branch for Day counting system, but the characters of Day Stem-Branch were found on Oracle bones. The Stem-Branch was applied into the Month and Year system around 206 B.C. (between the Chin and Han dynasties). The astrology animal names was assigned in Han dynasty.
Metal, Water, Wood, Fire and Earth are called Five Elements. Ancient Chinese Five Elements scholars observed yearly weather, farmer's activities and plant's life cycle in China, which is in the northern hemisphere. They found that the cycle of "to born in spring, to grow in summer, to harvest in the fall and to hide in the winter" can apply on Five Elements area.
Base on the theory of Yin Yang, Yin and Yang coexists all the time. Ancient Chinese distinguished Five Elements into Yin and Yang groups.
|Order||Symbols||Calendar Symbols||Pronunciation||Pictographic Characters|
|1||Yang Wood||Jiǎ||Yang seed spouts from the ground|
|2||Yin Wood||Yǐ||Young and tender stem grows|
|3||Yang Fire||Bǐng||Sunshine on the plant|
|4||Yin Fire||Dīng||Tree grows like a man|
|5||Yang Earth||Wù||Flourishing tree and plant|
|6||Yin Earth||Jǐ||Fruit on the bending stems|
|7||Yang Metal||Gēng||Cut and keep the crop|
|8||Yin Metal||Xīn||Prepare crop to different food on the table|
|9||Yang Water||Rén||Yang livings hide under the ground|
|10||Yin Water||Guǐ||Complete close like pregnancy, wait for spout|
The 10 Chinese characters were developed from the ancient pictographic characters. From the following chart, we can see the meaning of the characters have the relationship with the cycles of farmer's activities with plant during the year.
|Chinese Characters||Pronunciation||Chinese Pictographic Characters|
|Jiǎ||Yang seed spouts from the ground|
|Yǐ||Young and tender stem grows|
|Bǐng||Sunshine on the plant|
|Dīng||Tree grows like a man|
|Wù||Flourishing tree and plant|
|Jǐ||Fruit on the bending stems|
|Gēng||Cut and keep the crop|
|Xīn||Prepare crop to different food on the table|
|Rén||Yang livings hide under the ground|
|Guǐ||Complete close like pregnancy, wait for spout|
The sequence of these 10 characters is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. That means they are a decimal counting system. One king was named , which means Kon First, in 1897 B.C. of Yin Dynasty. More than 20 kings in Shang Dynasty (1783 - 1185 B.C.) used these 10 characters as their names.
Because these 10 character symbols are the counting numbers, they are borrowed to Chinese calendar. Chinese call them Ten Stems.