Abstract. Long-term urban extent data are highly desirable for understanding
urban land use patterns. However, urban observation data based on remote
sensing are typically confined to recent decades. In this study, we advance
in this arena by reconstructing the walled cities for China that extend
from the 15th century to the 19th century based on multiple historical
documents. Cities in late imperial China (the Ming and the Qing dynasties,
1368–1911) generally had city walls, and these walls were usually built
around the built-up urban area. By restoring the extent of the city walls, it
is helpful to explore the urban extent in this period. Firstly, we collected
the years of construction or reconstruction of city walls from the
historical data. Specifically, the period in which the size of the city
wall remains unchanged is recorded as a lifetime of it. Secondly,
a specialization on the extent of the city wall could be conducted based on the
urban morphology method and a variety of documentation, including the
historical literature materials, the military topographic maps of the first
half of the 20th century, and the remote sensing images of the 1970s.
The correlation and integration of the lifetime and the spatial data
led to the creation of the China City Wall Areas Dataset (CCWAD) for the late imperial period. Based on the
proximity to the time of most of the city walls, we selected six
representative years (i.e., 1400, 1537, 1648, 1708, 1787, and 1866) from
CCWAD to produce the China Urban Extent Dataset (CUED) for the
15th–19th centuries. These datasets are available at https://doi.org/10.6084/m9.figshare.14112968.v3 (Xue et al., 2021).