Why did Beijing Siheyuan become a typical representative of residential buildings in China?

Beijing quadrangles are famous all over the world. In old Beijing, besides the Forbidden City, royal gardens, temples, temples and palaces, a large number of buildings are the homes of countless people. An Examination of Sun's Old Stories quotes a poem from Yuan Dynasty: "Clouds open and close three thousands of feet, and there is a great height in the fog." This "one million family" house is now called Beijing Siheyuan. Why is it called "Siheyuan"? Because this kind of house has four rooms: the main room (north room), the inverted seat (south seat), the east wing and the west wing, which are surrounded on all sides to form a zigzag shape with a central courtyard inside, this quadrangle-style house is called quadrangle. Siheyuan has a long history in China. According to the analysis of existing cultural relics, quadrangle architecture appeared as early as 2000 years ago. In the process of historical development, China people especially like quadrangles, which are not only used in palaces, temples and government offices, but also widely used in local houses. However, as long as people mention quadrangles, they will naturally think of Beijing quadrangles. Why? This is a regular and typical quadrangle in Beijing. Among all kinds of quadrangles, Beijing quadrangle can best represent its main characteristics. First of all, the central courtyard of Beijing Siheyuan is basically square in plan, but some houses in other areas are not. For example, the courtyards of quadrangles in Shanxi and Shaanxi are vertical rectangles long from north to south and narrow from east to west, while quadrangles in Sichuan and other places are mostly horizontal rectangles long from east to west and narrow from north to south. Secondly, the houses in the east, west, south and north directions of Beijing Siheyuan are independent, and the east and west wing rooms are not connected with the main building and the inverted building itself. Moreover, the main building, wing room, inverted building and other houses are all on the first floor. There are no buildings, only the veranda at the corner connects these houses. In this way, the Beijing quadrangle has a bird's eye view from the air, just like four small boxes enclosing a yard. In many quadrangles in the south, the surrounding houses are mostly buildings. At the four corners of the courtyard, the houses are connected together, and the houses in the east, west, north and south do not exist independently. Therefore, southerners call the courtyard "patio", which shows that the courtyard in the south of the Yangtze River is as small as a well, which inevitably reminds people of the idioms of "frog in the well" and "sitting in the well and watching the sky". Beijing quadrangle is a veritable quadrangle, spacious and open, with plenty of sunshine and broad vision. Another point is that the cultural connotation of Beijing Siheyuan is rich, which fully embodies the traditional living concept of China. For example, the quadrangles of the Han nationality in Northeast China (rural quadrangles in Northeast China) conform to the first two characteristics of Beijing quadrangles, but do not have the characteristics of rich cultural connotations. For example, the single-door quadrangle in Northeast China (in China, the tradition is mostly in the form of double doors) and the practice of setting an "inverted door" behind the hall as a storage room all make people feel that it is a continuation of the poor habits brought by immigrants who "ran to Kanto" in Shandong and other places in the Qing Dynasty. It is precisely because of the above characteristics that people often regard Beijing Siheyuan as a typical representative form of China Siheyuan dwellings.