Four sides means that there is an open space between the four sides of the house and the wall, forming a backyard and a front yard. According to Feng Shui theory, the front yard should be open and bright, and giant trees and dead trees should not be planted. The rear is the Xuanwu side, and the emphasis is on reversing.
The plane of ancient buildings in China is rectangular. Rectangular buildings have two dimensions on the plane, namely width and depth.