Maps have been an important part of empire in China for a long time. In the Warring States period spies were always trying to steal maps, and defeated states presented maps of their territory to the victors as a sign of submission. Geographic knowledge written down in books like the Classic of Mountians and Seas was avidly collected as a way of learning the universal patterns of the universe. Needless to say there has been a lot written in the last decade or so about how cartography connects to empire, as it fits in so well with whole postmodern power/knowledge thing. To map a place is to control it, and thus empire-builders were always interested in mapping. I have not found many better visual representations of this than this map of Russian cartography on China, found on the CHGIS site.
The map shows the level of detail in Russian maps of China as of 1918. You can see that they were going to great lengths to get information about Manchuria, and that various military and scientific expeditions were bringing back good data from Mongolia and Tibet. It would be interesting to make up maps like this for British and French and Japanese (and Chinese) knowledge of China, but for now this is all we have.