Mongolia

Before it became a country, Mongolia was known foremost as a region of Asia defined by its central region, the Gobi Desert, and the surrounding steppe landscape. The borders of the Mongolian steppe touches provinces of China on the west and east, Siberia on the north, and the Great Wall of China on the south. It may represent the greatest expanse of largely unchanged grassland in the world, supporting wolves, corsac foxes, great bustards, steppe eagles, saker falcons, Mongolian gazelles, and several rare species of crane. In one of the world's last massive migrations, Mongolian gazelles cross this landscape by the millions. The history of Mongolia is punctuated with empires built by warlords who swept from the steppe on horseback into southern China, conquering the countryside. The greatest of these was Genghis Khan, who in 1205 united the Mongol tribes into one of the greatest empires the world has ever seen.

From the game's History encyclopedia, AoE3: DE 100.19.18309.