Although 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 Northern Russia to the North, China, and, the Middle East and Central Asia to the South. These steppes usually were inhabited by bands of nomads, sometimes united in confederations of varying sizes. These nomads usually herded animals, traded, raided more agricultural peoples and each other. However, every now and then, there would form giant nomadic confederations that threatened China, and sometimes the Middle East, Europe and beyond, but these confederations, while vast, and often destructive, rarely lasted, though they did redistribute peoples and disrupt the politics of the regions they attacked. The people in the Mongolia region usually focused their attention on nearby, wealthy China, and their occasional confederations greatly influence Chinese history. China’s response is a major theme in Mongolian history. The most notable alliance of the Mongols however 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.
In Mongolia itself, the legacy of Genghis Khan was a superior law code, a written language, and a historical pride. In addition, the foreign contact created by the Mongolian empire allowed for the spread of Mongolian genes, and the introduction of Buddhism into Mongolia. When the Mongolian empire broke up, Mongolia became part of the Yuan dynasty (1271–1368 CE), which included a unified China. The Ming Dynasty replaced it in 1368 and invaded Mongolia, leading to a Mongolian defeat, but not a Chinese conquest.
By the early 15th century, Mongolia was split between the Oirad in the Altay Mountains region and the eastern group that later came to be known as the Khalkha in the area north of the Gobi. In the mid-15th century, the Oirad dominated and briefly united Mongolia and threatened China, at one point taking a Chinese emperor captive. Eventually in the 16th century, under Dayan Khan, it ruled over a vast section of North-Central Asia from the Ural Mountains to Lake Baykal, conquering even the Khalkas. But after his death, Mongolia split into waring factions again, though most of Mongolia was unified by Altan Khan, who continued the Mongolian tradition of attacking China, though he gave up in 1571, signing a peace treaty with the Ming Dynasty that ended 3 centuries of war. Instead he concentrated on his southwest and raided Tibet, eventually becoming a convert to Tibetan Buddhism and naming the first Dalai Lama.
By the end of the 17th century the power of the khan had been greatly weakened. The Mongols were decentralized and threatened by a rising Manchuria. The last of the major khans, Ligden Khan established the pre-eminence of his faction over the Khalkha Mongols, and this prompted fear among his rivals who called upon the Manchu empire to help. The Manchus made some conquests in Eastern Mongolia, but Ligden was able to stop conquest further west. After his death, southern Mongolian resistance collapsed.
Over the 17th century, Mongolia became increasingly Buddhist, and one faction established a protectorate over Tibet. But as the Manchus became the Qing dynasty and established a firm control over China, they expanded into Northern Mongolia.
Qing rule over the areas of Northern Mongolia that became Outer Mongolia ended in 1911, with the fall of the Qing dynasty. Outer Mongolia briefly established a theocracy in 1911, before being conquered by a Chinese warlord in 1919, and then the Russian White movement warlord Ungern von Sternberg in 1920. The Red Army backed native guerrilla units led by Damdin Sühbaatar and the MPRP (the recently-founded local communist party), which defeated the forces of Ungern von Sternberg and founded the Mongolian People’s Republic, perhaps the first Soviet satellite.
With the fall of the Soviet Union, Mongolia lost its only major source of aid, but began political reforms.