How did the ancient astrologers in China make "astronomical division"?

Astronomical division is also a part of ancient astrology theory. In order to predict the good or bad of the world with the change of astronomical phenomena, ancient astrologers in China called the "dividing line" by corresponding the starry sky region with the countries and states on the ground. According to China's ancient astrology, every county and country on the earth corresponds to a certain area in the sky, and the astronomical phenomena in that area indicate the good or bad luck of every place. The law corresponding to heaven and earth is the theory of dividing line. The concept of dividing line has a long history. Li Zhou Guan Chun Zong Bo has records of "the stars distinguish the land of Kyushu" and "seeing demons in the world". It has begun to correspond different stars in the sky with different States and countries on the earth. The division in the sky is roughly based on 28 12 star hotels, and the ground is based on countries or regions.

There are many records about the division of astronomical geography in ancient books. For example, the division of astronomical geography in the Spring and Autumn Period and the Warring States Period recorded in Hanshu Geography is: Wei, Gou and Shen; Zhou, Liu, Qixing and Zhang; North Korea, horn, sound and mutual division; Zhao Di, the dividing line of Zambi; Yan Di, tail and basket points; Qi, air and danger; Song land, the teacher of the heart; The boundary between the garrison, the camp and the east wall; Chu, wing, car; Wu, fight and divide; Guangdong, the dividing line between Petunia and Five Girls.

In fact, there is no fixed pattern for grouping the corresponding relationship between heaven and earth. For example, only eight countries are listed in Shi Ji Tian Guan Shu, in which besides the correspondence between regions and stars, the correspondence between five stars and countries is also recorded. After the establishment of the correspondence between heaven and earth, astrology has a foundation. In this way, when the stars in a certain area or that day appear abnormal astronomical phenomena, such as fire, flood, military disaster, plague, etc. What is reflected by it will have a corresponding area predicted.