Continental Asia is divided into four regions: the taiga (northern forest); the steppe (treeless pasture); the desert; and the river valleys of the south. The steppe, an unwooded pasture or grassy plain, broken by a few well-defined mountain ranges, was the traditional home of the nomads who followed their horses, cattle, sheep and goats; always seeking new pastures for their animals. The Mongols were only one of the many pastoral nomad tribes of the steppe.

The heartland of the Mongols lay in northeast Asia, between the northern edge of the T'ien Shan and the southern edge of the Altai mountain ranges, where the Onon and Kerulen rivers flowed. It was separated from China by the Gobi Desert, where it is said lakes and rivers could dry up before the eyes of travelers and sand dunes might shift in the course of the night. It was harsh and unfriendly, with excessive heat in the summer and biting cold in the winter. Temperatures ranged from 40 degrees below in the winter to over 100 degrees in the summer and even then bitter winds from Siberia blew down with incredible suddeness. The steppe was only slightly more hospitable than the desert.

Some areas of the steppe were extremely mountainous; the rest was flat, with mostly sandy soil and gravel, and in some sections there were a few trees. In the spring it was covered with rich green grass, studded with many-colored flowers. By July an intense heat would shrivel the vegetation and turn the landscape a dull yellow-brown. Winter came in October and by November the waters would be frozen, not to thaw until April. No matter what the season, mountain and steppe alike were swept by winds so strong it was said they could nearly blow a rider from his horse. The weather was unpredictable. In the middle of the summer, severe thunder and lightning caused the death of many men while at the same time there could be very heavy snowfalls. Hail storms frequently caused much property damage.