From steppe tribes to an empire
In the early thirteenth century the grasslands of what is now Mongolia were home to several rival confederations of herders and hunters. Around 1206, after years of warfare and alliance-building, a leader known to history as Genghis Khan was acknowledged as ruler of the united Mongol peoples. Over the following three generations, Mongol armies and their allies took control of territory stretching from the Pacific coast of Asia toward Eastern Europe and the Middle East. It was the largest contiguous land empire in history, though its borders shifted constantly and it never worked as a single unified state for long.
The conquests were not a single campaign but a series of them, driven by different commanders, in different decades, against very different opponents. Seeing them as separate stages makes the whole story easier to follow.
First stage: North China and Central Asia
The first major target was northern China. From about 1211 the Mongols attacked the Jin dynasty, a state ruled by a people from Manchuria, and gradually took its cities and territory. The Jin capital region fell under Mongol control in the 1210s, though the Jin state did not finally disappear until the 1230s.
The next great campaign was against the Khwarazmian empire, which controlled much of Central Asia and Iran. Traditionally the war is said to have begun after Khwarazmian officials killed Mongol-sponsored merchants and envoys. From about 1219 to 1221 Mongol armies took famous cities such as Bukhara and Samarkand and pushed deep into Khurasan. These campaigns left a reputation for destruction that contemporary chroniclers described in grim terms. Modern historians treat their figures for the dead cautiously, since medieval authors often exaggerated, but there is little doubt that the damage was severe.
Second stage: Succession and the western push
Genghis Khan died in 1227, during a campaign against the Tangut state of Xi Xia. His son Ögedei was chosen as great khan a couple of years later, and the expansion continued. Korea came under heavy pressure, and the war against the Jin was concluded.
In the late 1230s a large army under Batu, a grandson of Genghis Khan, with the experienced general Subutai as its guiding strategist, turned west. It crushed the principalities of Kievan Rus, one by one, and then moved into Central Europe. That campaign, and the abrupt end of it, is covered in our account of the Mongol invasion of Europe. The territories Batu held north of the Black and Caspian Seas became the base of what later writers call the Golden Horde.
Third stage: Persia, Baghdad and Syria
In the 1250s a new push went southwest under Hülegü, a grandson of Genghis Khan. He destroyed the Nizari Ismaili strongholds in Iran and then marched on Baghdad, whose capture in 1258 ended the Abbasid caliphate as a political power in Iraq. The armies went on into Syria. Their advance was checked in 1260 at Ain Jalut in Palestine, where a force from the Mamluk sultanate of Egypt won a significant victory. Historians still discuss how decisive this battle was. The Mongol army there may have been relatively small, and political events elsewhere in the empire also pulled Hülegü’s attention away. Even so, the Mongols never conquered Egypt.
Fourth stage: Song China and the sea
In China, Kublai Khan, another grandson of Genghis Khan, took the title of great khan in 1260 and later declared the Yuan dynasty, in about 1271. The Song dynasty in the south, wealthy and well defended by rivers and walled cities, resisted for decades. It fell in 1279 after a long and expensive war that included major naval operations.
The Mongols also tried to extend their reach over water, with mixed results. Two attempted invasions of Japan, in 1274 and 1281, failed, and Japanese tradition credits storms for much of the damage. Expeditions to Southeast Asia and Java in the later thirteenth century also produced little lasting control.
Why the conquests succeeded
Historians generally point to a mix of factors rather than one cause:
- Military organization. Disciplined mounted archers moved fast and coordinated well, as described in our piece on horse archers.
- Adaptability. The Mongols quickly absorbed siege engineers and other specialists from conquered peoples, particularly from China and the Islamic world.
- Political circumstances. Many of their opponents were divided. The Song, the Jin, the Khwarazmians and the Russian princes were often at odds with neighbors or within their own ruling circles.
- Terror and negotiation. Cities that surrendered were often treated more leniently than those that resisted. This was a deliberate policy, although the actual outcomes varied.
Fragmentation
After the death of Möngke, the fourth great khan, in 1259, disputes over succession split the empire into several major khanates: the Yuan in China and Mongolia, the Ilkhanate in Iran and neighboring regions, the Chagatai Khanate in Central Asia, and the Golden Horde in the west. They often cooperated and sometimes fought each other. Over time the rulers adopted local religions and customs, with many in the western khanates becoming Muslim and the Yuan court leaning toward Buddhism.
The Yuan dynasty lost China in the 1360s, and the Ilkhanate had already broken up in the mid-fourteenth century. The Golden Horde lasted longer but gradually splintered into smaller khanates. Later conquerors, including Timur, claimed Mongol legacy, but the original empire was gone.
Effects on the wider world
The conquests were violent, and they caused major population losses and urban destruction in several regions. Estimates of the dead vary widely and should be treated with care. At the same time, a large connected zone under Mongol authority made the movement of merchants, envoys and missionaries easier, as discussed in the account of the Pax Mongolica. Some historians have also suggested that these long-distance links helped carry the Black Death across Eurasia in the fourteenth century, though the exact route and timing remain debated.
Other regions felt the Mongol shadow without being conquered. The Delhi Sultanate in northern India faced repeated Mongol raids, and the Kingdom of Hungary was devastated and then rebuilt itself with stone castles. The conquests also reshaped Russian politics for roughly two centuries and changed the balance of power across the medieval world.