The Origins of the Chinese Lunar Calendar: From Huangdi Calendar to Gan-Zhi Calendar
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The origin of the Chinese lunar calendar can be traced back to the Huangdi Calendar. It is said that after the Yellow Emperor (Huangdi) defeated Chiyou and unified the world, he ordered the creation of a calendar. Therefore, the first year of the Huangdi Calendar is the year when Huangdi ascended the throne, which corresponds to 2698 BCE in the Western calendar.
The Huangdi Calendar, along with the Zhaoxu Calendar, Xia Calendar, Yin Calendar, Zhou Calendar, and Lu Calendar, is collectively referred to as the “Six Ancient Calendars.” However, before the “Six Ancient Calendars,” there were two other methods of timekeeping, known as the Solar Calendar and the Lunar Calendar.
The Solar Calendar is said to have been created by the legendary Fuxi and is also known as the Jia Calendar or the Shangyuan Calendar. This calendar is based on the sun’s movement and uses the “Ten Rods Shadow Measurement Method,” dividing the year into ten months, with each month having a fixed 36 days. This system of timekeeping has been passed down and is still used by the Yi people, so it is also called the “Yi People’s Ten-Month Solar Calendar.”
However, using the Solar Calendar results in an error of about 5 days every year. Initially, this might not have had much impact, but over time it became increasingly inaccurate and failed to reflect seasonal and climatic changes, which posed a challenge for agricultural planning. Due to the shortcomings of the Solar Calendar, Nuwa, according to legend, devised the more accurate Lunar Calendar based on the moon’s cycles.
In fact, this is where the “Nuwa Patching the Sky” myth originates. The Lunar Calendar, also known as the Yin Calendar or Moon Calendar, is based on the phases of the moon. One complete cycle of the moon around the Earth is considered one month.
The Lunar Calendar can accurately reflect tidal changes, but it does not have a “year” concept, and therefore cannot represent the four seasons.
The Gan-Zhi Calendar, also known as the Star Calendar or Jiazi Calendar, was developed based on both the Solar and Lunar Calendars. It uses the Big Dipper as a reference, and the rotation of the Dipper’s handle from east to west completes one cycle, marking one year. Additionally, the Ten Heavenly Stems and Twelve Earthly Branches are paired together to form 60 different combinations, which are used to mark the year, month, day, and hour.
In the Gan-Zhi Calendar, a 60-year period is a complete cycle, called a Jiazi. The year is also divided into 12 parts, corresponding to the “Twelve Months System.”
