Prior to World War I Outer
Mongolia, the large area in the top center of the map of China had
become independent, and Inner Mongolia was divided into four provinces
of China. The map, issued as one of a four stamp set with the same
design, shows Outer Mongolia as a province of China also, which, at
the time was not true. It had been independent since 1911. Whether the stamp reflects a Chinese claim to
the territory of Outer Mongolia, or was simply sort of carry-over from
an earlier time is not clear. In any case it is an error.