Twenty-eight lodging houses are divided into four groups according to the order in the above table, with seven lodging houses in each group, which are matched with four squares, four colors and four animal images respectively, and are called four elephants or four lands. The corresponding relationship between them is as follows: Oriental black dragon (or Qinglong), cyan; Northern Xuanwu (that is, tortoise and snake), black; Western white tiger, white; Southern Suzaku (or Suzaku), red.
Twenty-eight Hostels are matched with the four directions, which is based on the astronomical phenomena in the early twilight around the ancient vernal equinox. At this time, it was Zhu Bird who spent seven nights in the south, black dragon spent seven nights in the east, Xuanwu spent seven nights in the north and Baihu spent seven nights in the west. The matching of the four colors is related to the ancient five elements theory. As for the origin of the matching of dragons, turtles, snakes, tigers and birds, one view is that it is related to the totem of primitive tribes; Another theory is that it may be related to the seasonal characteristics represented by these constellations when they are unconscious. For example, seven nights in the south is spring, and birds can be regarded as a symbol of spring and so on.
in the summer of p>1978, an ancient tomb in the early years of the warring States period (dated to the 5th century BC) was excavated in Suixian county, Hubei province, which contained a lacquer box cover with the names of twenty-eight lodging houses and the corresponding images of Qinglong and White Tiger. This not only advances the time of the documentary record of the appearance of Twenty-eight Hostels, but also confirms that the origin of the four elephants matching Twenty-eight Hostels is also very early.