2. MONGOLIA AND SINKIANG
The area covered by the present-day Mongolian People’s Republic is a remnant of a much larger Mongolia, a vast, ill-defined expanse of steppe and desert once inhabited by tribes of barbarous nomads. United under the leadership of Genghis Khan at the turn of the 12th century, these tribes rode out from their homeland to devastate and subjugate much of Asia and Europe.
Today’s Mongolia corresponds to the region formerly known as Outer Mongolia, minus peripheral areas later assigned to Sinkiang, Tuva and Manchuria. During the period of Russian quasi-official and official postal activity (1865-1920), Mongolia comprised both Outer and Inner Mongolia, all of which had been under Chinese sovereignty since 1691. The boundary between Outer Mongolia and the Russian Empire had been fixed by the Treaty of Nerchinsk (1689) and further defined by the Treaty of Kyakhta (1727).
Inner Mongolia, since absorbed into the main body of China, may be loosely described as the region between the Gobi Desert of Outer Mongolia and the Great Wall of China. Built originally to keep out the Mongol hordes, for centuries the Great Wall was the traditional boundary between Mongolia and China proper. Nestling inside the Great Wall, the city of Kalgan was then the frontier post for the camel caravans bringing the mail from Russia, and like Kyakhta at the other end of the trail, features prominently in the postal history of the region.