The Xia calendar
is one of the ancient Han calendars. Together with the Huangdi calendar, the Zhuanxu calendar, the Yin calendar, the Zhou calendar and the Lu calendar, they are collectively known as the six ancient calendars.
It is said that the calendar was created by the Xia Dynasty, and the original calendar rules have been lost
Now we only understand some contents from some ancient books: the winter solstice month is used as the sub-month to calculate the beginning of the first year of the year , the calendar year starts with the month of Jian Yin, that is, Yin Zheng (later called Xia Zheng), which roughly uses an integer of 366 days as one year old, and uses the subtraction method and positive leap remainders to adjust the time difference.