The ancients roughly divided the sky into four regions: the stars in the east combined into the image of a dragon, called "green (pale) dragon"; The western stars combine to form the image of a tiger, which is called "white tiger"; The stars in the south combine to form an image of a bird spreading its wings and flying, which is called "Suzaku (bird)"; The stars in the north combine to form an image of turtles and snakes, which is called "Xuanwu".
The four ancient stars, Qinglong, Baihu, Suzaku and Xuanwu, refer to the names of the leaders of 28 constellations in the east, south, west and north directions near the ecliptic and the equator (the angle between the ecliptic and the equator is 23 degrees, 26 minutes and 33 seconds), of which 28 constellations are in charge.
There are seven accommodations in the east: Jiao, Kang, Bian, Fang, Xin, Wei and Fan. The leader is called Qinglong.