Huangdi Neijing was born in the Spring and Autumn Period, 2500 years ago. The book says there are 365 days in a year.

Chapter 9 of Huangdi Neijing, the theory of six Tibetan images;

Qi Bo said: The sky is Yang and the earth is Yin. The sun is sunny and the moon is cloudy. There is discipline in the industry, and Zhou makes sense. The day is one degree and the month is thirteen degrees. So the size of the month is 365 days, and the accumulated gas is full of leap.

It can be seen that the "365 days" in Huangdi Neijing is based on the day, which is what we call the solar calendar today, that is, the AD calendar. The lunar calendar in China is based on the month, which is what we call the lunar calendar today. Spring Festival, Lantern Festival and August 15th are all lunar holidays. New Year's Day and Christmas are festivals based on the AD calendar.

However, the western calendar was invented by westerners and the lunar calendar was invented by China people. However, Huangdi Neijing is consistent with the calendar year and the lunar calendar. What a coincidence. Let me say that the best explanation is: No matter whether it is the AD calendar, the lunar calendar or the Huangdi Neijing, it was not invented by westerners or China people, but by God.

After God invented two calendars-the solar calendar and the lunar calendar, he gave them to two people, one for each family. Distribute the solar calendar to westerners and name it AD calendar; For people in China, it's called the lunar calendar.