The calendar had been changed many times before the Han Dynasty, and only the Book of Rites, Moon Order, Huainanzi Astronomical Training written by Liu An in the Western Han Dynasty recorded 24 solar terms. Among the 24 solar terms, the day in beginning of spring is designated as the Spring Festival, which means that spring begins. This title lasted for more than 2000 years, until 19 13, when the national government officially issued a document, making it clear that the first day of the first month of the first month of each year was the Spring Festival. Since then, beginning of spring has only existed as one of the 24 solar terms, and it has been passed down to this day.