Sexagenary cycle

The sexagenary cycle (六十花甲 liùshí huājiǎ), also known as the "stems-and-branches" or "trunks-and-branches" (干支 gānzhī), is a traditional Chinese calendar system. It is a list of sixty terms which are used for identifying days or years.^[1]

The oldest Chinese system for recording and organizing time uses repeated periods of 60 days.^[2]

Ancient records show that the sexagenary cycle was used to count years in the 3rd century B.C.^[2]

The repeating series of 60 terms has been an important part of historical calendar systems in East Asia, including China, Japan, Korea, Tibet and Vietnam.

Each term in the sexagenary cycle is made up of two Chinese characters:

• One character is taken from a list of "heavenly stems" or "trunks" (天干 tiāngān), including wood, fire, earth, metal and water.^[3]
• The other character is taken from a list of "earthly branches" (地支 dìzhī) or animal signs, including Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, and Pig.^[4]
• The combinations make up a total of 60 different names for a period of time.

• Chinese Zodiac

• "The Chinese sexagenary cycle and the ritual origins of the calendar" Archived 2016-02-02 at the Wayback Machine
• "The Mathematics of the Chinese Calendar"