The twelve characters of the Chinese zodiac (十二支 aJūnishi), sometimes translated as earthly stems, appeared about 3,500 years ago. Initially, they were probably the twelve months of the year and later used for days and years. According to some historians, they were associated with the twelve animals about 2,000 years ago. The first year of the Chinese zodiac, later called the Year of the Rat, is always written as 子, not 鼠, because the former character did not carry the meaning of rat first.
十干 (じっかん), the ten characters of the Chinese astrology, sometimes translated as heavenly stems, are as old as the 十二支. The ancient Chinese believed that there were ten suns, each of which appeared once every ten days. 十干 were probably the names of the ten days and also used for months and years later. We still commonly use the word 旬 (じゅん), which means ten days, as in 上旬 (じょうじゅん), 中旬 (ちゅうじゅん), and 下旬 (げじゅん). They are now associated with 陰陽 (いんよう), the yin-yang dualism, and 五行 (ごぎょう), the Chinese five elements theory, as follows:
The kun-readings are better than the on-readings to avoid homonyms. Some of the associations of yin-yang are shown below:
It is clear that yin is zero, and yang is one in the binary system. Some of the associations of 五行 are shown below:
* The ancient Chinese calendar is about one month behind the Western calendar.
# The seasons are defined by the position of the sun, not temperature.
The earthly stems:
| 子年 | 【ねずみどし】 | Year of the rat |
| 丑年 | 【うしどし】 | Year of the ox |
| 寅年 | 【とらどし】 | Year of the tiger |
| 卯年 | 【うさぎどし】 | Year of the hare |
| 辰年 | 【たつどし】 | Year of the dragon |
| 巳年 | 【へびどし】 | Year of the snake |
| 午年 | 【うまどし】 | Year of the horse |
| 未年 | 【ひつじどし】 | Year of the sheep |
| 申年 | 【さるどし】 | Year of the monkey |
| 酉年 | 【とりどし】 | Year of the cock |
| 戌年 | 【いぬどし】 | Year of the dog |
| 亥年 | 【いのししどし】 | Year of the boar |
十干 (じっかん), the ten characters of the Chinese astrology, sometimes translated as heavenly stems, are as old as the 十二支. The ancient Chinese believed that there were ten suns, each of which appeared once every ten days. 十干 were probably the names of the ten days and also used for months and years later. We still commonly use the word 旬 (じゅん), which means ten days, as in 上旬 (じょうじゅん), 中旬 (ちゅうじゅん), and 下旬 (げじゅん). They are now associated with 陰陽 (いんよう), the yin-yang dualism, and 五行 (ごぎょう), the Chinese five elements theory, as follows:
The kun-readings are better than the on-readings to avoid homonyms. Some of the associations of yin-yang are shown below:
It is clear that yin is zero, and yang is one in the binary system. Some of the associations of 五行 are shown below:
The animals of the Eastern zodiac:
* The ancient Chinese calendar is about one month behind the Western calendar.
# The seasons are defined by the position of the sun, not temperature.
