Cities in 600 Years Ago

Using historical documents, ancient maps, survey maps of the Republican period, and remote sensing images, this paper restores the urban built-up area boundaries of the 56 cities in Jiangsu-Shanghai region since the Ming Dynasty. The paper selects the expansion rate, expansion intensity, power-law distribution index, fractal dimension, compactness, and migration distance of city gravity center to analyze the urban evolution process in terms of city scale and spatial form. At the same time, the paper uses the panel data model to analyze the possible factors that influence the expansion of urban built-up areas. The results show that: (1) the size of urban built-up areas in Jiangsu- Shanghai region has increased significantly over the past 600 years, and the total area of the study area has expanded by 59.9 times, among which the main city of Wuxi has expanded by 346.7 times; (2) the process of the expansion can be divided into five stages: the breeding stage, the embryonic stage, the initial stage, the acceleration stage, and the upgrading stage; (3) during the 600 years, the difference in the size of urban built-up areas in the study area tends to decrease, and the number of large cities has increased; (4) in terms of spatial form, with the expansion of city scale, the urban form has become more complicated, the fractal dimension has increased, and the compactness of the urban form has decreased; (5) regarding the shift of the city gravity center, most cities in the plain area have expanded around the original cities evenly and the migration distances of the gravity centers are less than 3.5 km; (6) the expansion of city scale is greatly influenced by local economy and population, and its correlation with the urban administrative level is weak; the urban form has become more complicated due to population growth and has no significant correlation with the urban economic level and the urban hierarchy.