Cave dwelling is a unique form of dwelling house on the loess plateau. It is the physical remains of the development and evolution of cave dwelling in the early stage of human beings. Pinglu cave building technique is a kind of representative. Cave dwelling is usually one or two hundred meters long and difficult to be permeated by water. The loess with strong orthogonality provides good natural conditions for cave dwelling.
There are many kinds of cave dwellings, which are mainly divided into Mingzhuang cave, earth pit cave, independent cave dwelling, cliff cave dwelling, sunken cave dwelling and so on. Cave building techniques are rich and varied. For example, flat-topped cave dwellings are built on flat ground with adobe or masonry. Cliff - type cave is built in the way that the side of a mountain slope is leveled vertically and chiseled and excavated in the flat surface. Courtyard cave dwelling is more exquisite. Generally, first, digging a hole on the flat ground for about 7-meter depth, square shape, and then digging in the bottom of the four walls of the hole so as to form the quadrangle residence courtyard.
The cave dwelling in Pinglu County of Shanxi Province is called cellar (underground) courtyard, also known as underground pit courtyard, patio cave courtyard, sunken cellar courtyard, etc. According to different uses, it can be divided into residential, storage, livestock, latrine and door opening cave dwellings, etc. Its construction techniques have a history of more than 4,000 years. "Seeing the tree but not the village, seeing the village but not the house, the cave dwelling produced out of the earth and the courtyard hidden in the ground", this ballad vividly depicts the characteristics of cellar yard.
