Is the age recorded in the history books a new calendar or an old calendar?

History textbooks use the Gregorian calendar.

Gregorian calendar (that is, your new calendar)

A.D. (English: Buyila; Latin: Anno Domini, abbreviated as A.D. or C.E.) is the Gregorian era, also known as Gregorian calendar or A.D., a method of chronology that originated in western society.

It began in the year when Jesus was born.

The date after the birth of Jesus is called AD (AD, abbreviated as C.E.), and the date before the birth of Jesus is called B.C.E

1949 On September 27th, the first plenary session of China People's Political Consultative Conference passed that the newly established People's Republic of China (PRC) adopted the Gregorian calendar and the Gregorian calendar commonly used in most countries in the international community as its own calendar and calendar year.

When you say old calendar, you should mean lunar calendar.

The lunar calendar in astronomy mainly refers to the calendar arranged according to the moon phase cycle. The calendar of the moon's one-week orbit around the earth (taking the sun as the reference object, the actual moon's orbit is more than one week) is January, that is, the first month of the lunar calendar is used as the basis for determining the calendar month, and a year is twelve calendar months.

In the process of calendar development and evolution, the emergence of 24 solar terms was used to scientifically guide agricultural production, and the lunar calendar (Han calendar) was formed. Although the lunar calendar and lunar calendar are commonly known as lunar calendar, ancient calendar, Han calendar, summer calendar and old calendar, there are differences between lunar calendar and lunar calendar (Han calendar). The traditional summer calendar (Han calendar) is actually a kind of yin-yang calendar. On the contrary, the Islamic calendar is a pure lunar calendar.

Lunar calendar is one of the traditional calendars in China, which is also called lunar calendar, ancient calendar, Han calendar, yellow calendar, summer calendar and old calendar. Many people always think that the lunar calendar is the lunar calendar (Chinese calendar), but it is not. The lunar calendar (Chinese calendar) we are talking about is a combination of yin and yang calendars and leap months, and there is no leap month in the lunar calendar.

The lunar calendar determines the moon according to the law of its movement: the orbit of the moon is called the white road, and both the white road and the ecliptic are two great circles on the celestial body, which intersect at five degrees and nine minutes. The moon goes around the earth and appears on the ecliptic twice, which lasts for 7 hours and 43 minutes 1 1.5 seconds on the 27th, and is called "Stellar Moon". Only when the moon revolves around the earth, the position of the earth also changes. The forward count is more than 27 degrees, and the moon runs 13 degrees 15 minutes every day, so it takes 12: 44: 2.8 to return to the moon on the 29th, which is called "the first moon", and it is called the moon according to custom, which means the first moon.