Ayaodong (窰[iɤ] in nativeJin Chinese,[1] or 窰洞[jɑʊtʊŋ]yáodòng in Beijing Mandarin) is a particular form ofearth shelter dwelling common in theLoess Plateau inChina's north. They are generally carved out of a hillside or excavated horizontally from a central "sunken courtyard".[2][3]
The earth that surrounds the indoor space serves as an effective insulator, keeping the inside of the structure warm in cold seasons and cool in hot seasons. Consequently, very little heating is required in winter, and in summer, it is as cool as an air-conditioned room.[4]
The history of yaodongs goes back centuries, and they continue to be used. As of the early 2000s, between 30 and 40 million people in northern China still lived in yaodongs,[5][6] a number rapidly decreasing as millions move to more modern dwellings nearby or move away as part ofurbanization in China.[7]
The landscape of theLoess Plateau terrain is very complicated, with valleys, slopes, ridges, and hillocks. In order to avoid the wind and utilize sunlight and water, most yaodongs are distributed along the sides of the cliffs and valleys to conform to the terrain – in principle, forming three types of Yaodong.[8][9]
Cliffside yaodongs are the most common among all types. People dig caves in the cliff on the edge of the loess slopes with the floor rectangular and the top arched. In front of the cave is an open space for lighting and ventilation, so that the user does not feel the space to be oppressive. According to the number of cave openings, the yaodongs can be further classified into the three-hole type, two-hole type, and single hole type. A typical example is the city ofYan'an.
Those dug around an excavation conducted at the surface, serving as interior courtyard, called yaodong-well or sunken courtyard. In theLoess Plateau, without hillsides and ravines available, peasants skillfully use loess's features (wall stability) to dig a square pit on the spot, and then dig the cave horizontally on the four walls to form the underground courtyard. In most parts of western Henan, this form of cave is called the "pit yard".
Sunken yaodongs have two types, according to the form of entrance: slope-entrance and flat-entrance. Both are excavations of pits in the flat ground. First, if the yaodong is surrounded by flat ground, a slope can be used for entering and leaving the pits. This is called the "dikenyuan" or the "pit courtyard" [zh] (Chinese:地坑院;pinyin:De kēng yuàn). Second, if there is a cliff or a steep slope next to the yaodong, it can be used to excavate the corridor through the cliff or slope to reach the horizontal entrance of the courtyard. This type of Sunken yaodong, which is also called the well-courtyard or the well-yaodong, is the majority in the area.
The Hoop yaodong, also called independent yaodong, is the most valuable type considering its construction techniques. In the traditional residential areas in westernHenan, the Hoop Yaodongs appear in the places where there are no conditions for excavations of cave dwellings, e.g. the loess layer is thin, the slopes are gentle, the height of the soil cliffs is insufficient, or the bedrock is exposed. A hoop yaodong is usually built wholly or partially outdoors, with an arched structure inspired by the underground dwellings. This arch-shaped form not only reflects the Chinese traditional thinking of aRound sky and Square earth, but more importantly, the high arch of the cave along with high windows allows the sun to further penetrate the cave in winter, therefore making full use of solar radiation. This new vaulted home of this type is now common among farmers in the area.
The first yaodongs were underground dwellings that date back to the2nd millennium BC, China'sBronze Age, and according to Chinese tradition, theXia dynasty. Chinese scholars generally believe that this type of habitat was developed mainly from theHan dynasty (206 BC to 220 AD) on, along with a progressive improvement of construction techniques during theSui (581 to 618) andTang (618 to 907) dynasties. During the dynastiesMing (1368 to 1644) andQing (1644 to 1912), the pace of construction reached its peak.[12]
The yaodong homes are common on theLoess Plateau ofChina in the North, and are found mainly in five provinces:Gansu,Shaanxi,Shanxi,Henan, and the Hui Autonomous Region ofNingxia. In theQingyang, Gansu region, the ratio of cave dwellers to non-cave dwellers is the highest found anywhere in China.
More elaborate yaodongs may have afaçade built with stones with fine patterns carved on the surface. Yaodongs can also be constructed with stones or bricks as stand-alone structures.[clarification needed] The inside walls are usually plastered with lime to make them white. Different types of yaodong have varying construction processes.[13]
The death toll of approximately 810,000 from the1556 Shaanxi earthquake is claimed to be in part because it was centered on the Loess Plateau, where many yaodongs collapsed.[14][15] Though yaodongs were found to have better earthquake resistance than some other types of dwelling common in the region, such asadobe buildings, at lower earthquake intensities wooden truss buildings collapsed at lower rates than yaodong.[16] As a result of the1920 Haiyuan earthquake both conventional homes and yaodongs collapsed, since neither type of dwelling common to the area was particularly earthquake resilient.[17] According to eyewitnesses, yaodongs withstood the1976 Tangshan earthquake better than conventional homes, attributed to the soft soil of the region. In Ningxia however, yaodongs were three times more likely to collapse during an earthquake compared to conventional homes. This was attributed to harder soil and the yaodongs being mainly located at the foot of valleys, vulnerable to landslides.[18]
The most famous yaodongs in China are perhaps those inYan'an.Edgar Snow visited Mao and his party in Yan'an and wroteRed Star Over China.
