Near the edge of the roof, a short wall of about 30 to 50 cm tall called "blocking horse wall" is built to prevent rainwater from running into the courtyard, as well as to protect children and people working on the ground. Shrubs like wild jujube are usually planted on the wall to prevent water erosion and for decoration.

The underground caves are cool in summer and warm in winter. Fully suitable to the local conditions, the residence is also wind-resistant and impervious to sound. Together with its low cost and high durability, the underground cave is an ideal dwelling on the Loess Plateau. Walking in any village on the tablelands, you can easily find underground courtyards that have bred several generations spanning over a hundred years.

  History

Though rarely seen today, the underground village boasts a history of over 4,000 years, and was once a prevailing residence in West Henan Province, South Shanxi Province, North Shaanxi Province and East Gansu Province on the vast Loess Plateau along the Yellow River. Today, the residence is largely remaining on the outskirts of Sanmenxia City in the western part of Henan Province.

The underground village probably originated from the troglodyte (cave-dwelling) tradition of ancient Chinese people. With the development of the economy and society, the number of underground villages is declining. In the late 1980s, the disadvantages of underground villages including insufficient lighting and inconvenient transportation as well the improved economic condition elsewhere all contributed to the increasing abandonment of the cave dwellings. The original underground villages are being replaced by modern buildings.

Many cave dwellings are either filled up or have collapsed with more people turning to modern buildings. Still, the residence form has been best preserved in the Sanmenxia region. Underground villages are scattered across the vast area of the loess plateau. On the Dongfan, Zhangcun and Zhangbian tablelands in Shan County, two-thirds of the local villagers are still living in the underground caves.