The historical maps and the maps of China's provinces (any maps without sources given) were all specially made for this site.  The base contour map was created by tracing the map of China on p. 56 of the 1968 Britannica World Atlas.  Province boundaries and approximate historical boundaries were drawn freehand by consulting other reference works, such as the Zhongguo lishi ditu ji series.  No attempt has been made to take into account the changes in the coastline over the centuries, as all the maps are made from the same base map.