Sexagenary cycle

The Chinese sexagenary cycle (zh-cp|c=干支|p=gānzhī) is a cyclic numeral system of 60 combinations of the two basic cycles, the ten Heavenly Stems (天干; tiāngān) and the twelve Earthly Branches (地支; dìzhī).

This traditional Chinese calendrical system is used as a means of numbering days and years, not only in China but also in other East Asian nations like Japan, Korea, and Vietnam. The Sexagenary system is also important in Chinese astrology and Chinese fortune telling.

Overview

The cycle was used in China since the second millennium BC (it has been found on Shang dynasty oracle bones), as a means of "naming" days (just as we use the days in the week). This use of the cycle for days is attested throughout the Zhou dynasty. For instance, most entries in the Spring and Autumn Annals use this system. Its use for recording years is more recent. It became widespread in the Western Han Dynasty (202 BC- 8 AD), and might have begun in the late Warring States period. The year 1984 began the present cycle, and 2044 will begin another.

In Japan, according to "Nihon shoki", the calendar was transmitted to Japan in 553. But it was not until the Suiko era that the calendar was used for politics. The year 604, when the Japanese officially adopted the Chinese calendar, was the first year of the cycle.Fact|date=January 2008

The calendar is calculated by combining the nihongo|"jikkan"|十干|the 10 stems and nihongo|"jūnishi"|十二支|the 12 branches. These two sets of terms were used to enumerate years of the civil calendar. Combining the series form a greater cycle of 60 terms, as the least common multiple of 10 and 12 is 60. The first term is formed by adding the first stem to the first branch, then the second stem to the second branch, and so on. If you start with nihongo|kinoe-ne/kōshi|甲子, so the 61st year would also be kinoe-ne. This was how the tradition of celebrating nihongo|the 60th birthday|還暦|kanreki began. This counting system employing things of nature and animals create many myths, and people of Japan today still consider the good and bad luck of certain days and years.

Ten Heavenly Stems

The sexagenary cycle was first used for days in the Shang Dynasty, and later also used for years and less commonly for months.

For example, the year 2000 was the 17th year of the 78th sexagenary cycle, a gēng-chén year (庚辰年), a year of the Yang Metal Dragon. Therefore, 2006 is the 23rd year of the 78th sexagenary cycle, called a bǐng-xū year (丙戌年), a year of the Yang Fire Dog; 2007 a year of the Yin Fire Pig.

The naming of the months and days is not common now, although they are shown on Chinese calendars and almanacs.

*Attention: In common practice, the "combination" elements (Chinese agricultural calendar) should be applied for the Sexagenary Cycle. Either the "Heavenly Stem" or the "Earthly Branch" alone is not enough to determine the element for any year within the 60 years of the Sexagenary Cycle.
** The writing of "Yang Earth Rat"("e.g.", 2008), "etc.", is not recommended for use, because people might misinterpret "Earth" as the "Element" of that year (2008).

Relation to the western calendar

Below is the sexagenary cycle matched up to the Western calendar for the years 1804 - 2043, or four full 60 year cycles.

1804 - 1923

1924 - 2043

ee also

* Chinese calendar
* Lunisolar calendar