With the assistance of so many talented personnel, the Human Tribe prospered under the governance of Yao. During the preliminary period of Tang Yao's administration, the astronomical calendar was not quite ideal, so the populace often missed the farming seasons. Therefore, Yao commanded the Xi's and the He's to observe the Heaven's will and enacted a calendrical system according to the appearance of the sun, the moon and the positions of stars. This taught the men which season was the right time to take part in production.
The Xi's and He's mastered astronomy and calculated the time and date according to celestial phenomena and climatic phenology like the movements of the sun, the moon, the stars and so on. They also determined the four seasons, where a cycle for the moon is a month, a cycle for the sun is a year, and that there are 366 days in a year. This was the earliest calendar recorded in our country, which laid a foundation for the lunar calendar in China.
