Why doesn't the perpetual calendar match the old yellow calendar?

"Ten thousand years" in the perpetual calendar means that the time span is very long, but it doesn't really mean ten thousand years, but the time recorded in the perpetual calendar is still longer than that in the Gregorian calendar, including at least 100 years of Gregorian calendar, lunar calendar, Tibetan calendar and other calendars, as well as information related to the Gregorian calendar, such as good or bad luck, holidays, reminders and so on.

Generally, the yellow calendar is printed and published on a yearly basis, and it can also display many sets of calendars, such as solar calendar, lunar calendar, and dry calendar. There are a lot of rules and contents related to seeking good fortune and avoiding evil.

The yellow calendar belongs to a kind of perpetual calendar. Perpetual calendar: the oldest solar calendar in ancient legends of China, which records the dates of specific solar and lunar calendars within a certain time range (such as 100 years or more) for the convenience of people in need. Ten thousand years is just a symbol, indicating a long time span.

Extended data:

In modern times, the main contents of the yellow calendar include: Gregorian calendar, lunar calendar and trunk calendar, trunk and branch calendar, twenty-four solar terms, twelve gods, week, orientation and so on. That is, people in ancient China recorded their daily likes and dislikes on the calendar as a guide to action.

China's traditional calendar is based on heavenly stems and earthly branches's arrangement, combination and circulation, which means circulation and reappearance. It is this "recurrence" that makes it meaningful to choose a date to avoid it. The fundamental basis for the ancients to formulate calendars and determine auspicious days is the sun, the moon and the stars.

Baidu Encyclopedia-Huangli

Baidu encyclopedia-perpetual calendar