Average temperatures over most of the country are below freezing from November through March and are about freezing in April and October. January and February averages of -20° C are common, with winter nights of -40° C occurring most years. Summer extremes reach as high as 38° C in the southern Gobi region and 33° C in Ulaanbaatar. More than half the country is covered by permafrost, which makes construction, road building, and mining difficult. All rivers and freshwater lakes freeze over in the winter, and smaller streams commonly freeze to the bottom. Ulaanbaatar lies at 1,351 meters above sea level in the valley of the Tuul Gol, a river. Located in the relatively well-watered north, it receives an annual average of 31 centimeters of precipitation, almost all of which falls in July and in August. Ulaanbaatar has an average annual temperature of -2.9°C and a frost-free period extending on the average from mid-June to late August.

Mongolia’s weather is characterized by extreme variability and short-term unpredictability in the summer, and the multiyear averages conceal wide variations in precipitation, dates of frosts, and occurrences of blizzards and spring dust storms. Such weather poses severe challenges to human and livestock survival. Official statistics list less than 1 percent of the country as arable, 8 to 10 percent as forest, and the rest as pasture or desert. Grain, mostly wheat, is grown in the valleys of the Selenge river system in the north, but yields fluctuate widely and unpredictably as a result of the amount and the timing of rain and the dates of killing frosts. Although winters are generally cold and clear, there are occasional blizzards that do not deposit much snow but cover the grasses with enough snow and ice to make grazing impossible, killing off tens of thousands of sheep or cattle. Such losses of livestock, which are an inevitable and, in a sense, normal consequence of the climate, have made it difficult for planned increases in livestock numbers to be achieved.

History
MONGOLIA and the Mongol people have periodically been at the center of international events. The histories of nations–indeed, of continents–have been rewritten and major cultural and political changes have occurred because of a virtual handful of seemingly remote pastoral nomads. The thirteenth-century accomplishments of Chinggis Khan in conquering a swath of the world from modern-day Korea to southern Russia and in invading deep into Europe, and the cultural achievements of his grandson, Khubilai Khan, in China are well-known in world history. Seven hundred years later, a much compressed Mongolian nation first attracted world attention as a strategic battleground between Japan and the Soviet Union and later between the Soviet Union and China. In the 1980s, the Mongolian People’s Republic continued to be a critical geopolitical factor in Sino-Soviet relations.

The Mongols arose from obscure origins in the recesses of Inner Asia to unify their immediate nomadic neighbors and then to conquer much of the Eurasian landmass, ruling large parts of it for more than a century. Emerging from a newly consolidated heartland north of the Gobi in the thirteenth century, the Mongols and their armies–made up of conquered peoples–thrust through western Asia, crossed the Urals, invaded the countries of Eastern Europe, and pressed on to Austria and the Adriatic. They also advanced through southwest Asia to the eastern Mediterranean and conquered the Chinese empire. Around the same time, they embarked on ambitious maritime expeditions against Java and Japan. The Mongols were phenomenally hard driving and ambitious for such a small group and their accomplishments were considerable. Only the Mamluks of Egypt, the “divine winds” of Japan, and the Mongols’ own legal tradition–the need to elect a new khan–halted the inexorable Mongol advances.