How did the twenty-four solar terms come into being?

The setting of 24 solar terms is a unique creation in the ancient calendar system of China. It correctly reflects the objective law of alternation of four seasons in a year and alternation of cold and summer, and is of great significance to guiding agricultural production and handicraft production.

At the latest, in the Spring and Autumn Period of the 7th century BC, the concept of solar terms came into being and began to be adopted by calendars. However, due to the separatist regime in the Spring and Autumn Period and the Warring States Period, the solar terms set by national calendars are not uniform, with 8 solar terms and 30 solar terms. The current 24 solar terms system was established at the turn of Qin and Han Dynasties at the end of 3rd century BC.