While people have inhabited Mongolia since the Stone Age, Mongolia only became politically important after iron weapons entered the area in the 3rd century B.C. In general, Mongolia at this point had a similar history to the rest of the nomadic steppe that lies between Siberia and Northern Russia to the North and China, the Middle East, and Central Asia to the South. The steppes usually were inhabited by bands of nomads, sometimes united in confederations of varying sizes. These nomads usually herded animals, traded, and raided agricultural peoples and each other. However, every now and then, they would form giant nomadic confederations that threatened China, and sometimes the Middle East, Europe and beyond. These confederations, although vast and often destructive, rarely lasted. but they did redistribute peoples and disrupt the politics of the regions they attacked. The people in the Mongolian region usually focused their attention on nearby, wealthy China, and their occasional confederations greatly influenced Chinese history. China's response is a major theme in Mongolian history. The most notable alliance of the Mongols reached far beyond China, under the leadership of Genghis Khan. His empire and the states that emerged from it would play a major role in the history of the 13th and 14th centuries. He and his immediate successors conquered nearly all of Asia and European Russia and sent armies as far as central Europe and Southeast Asia.

Chinggis Khan was born as Temujin in c. 1162, near Burkhan Khaldun mountain, not far from where Ulaanbaatar stands today. He united the Mongol tribes and was procalimed Chinggis Khan ('Universal Ruler') at the Ikh Kuriltai (Great Council) in 1206, and went on to conquer an empire of 26 million square kilometres, four times the size of the Roman empire, before his death. He died in 1227, and, like many events of his life, the exact circumstances are surrounded in mystery and legend.

ongolia's main three religions are Tibetan Buddhism, Islam, and Shamanism, and there is also now a growing Christian population. Because of the varying degrees to which one can adhere to Buddhism (unlike some other religions which clearly demarcate their followers), the population of Mongolia is variously described as 50% Buddhist and 40% non-religious, with the remainder being Muslim, Shamanist or Christian, or as being 90% Buddhist.