Mongol invasions and conquests
The year 1206 marked the moment Temujin became Genghis Khan, uniting warring Mongol tribes into a single force. This unification did not happen in isolation but followed fifteen years of unusually wet and warm weather from 1211 to 1225. These climatic conditions allowed horses to breed in unprecedented numbers across the steppes. A horse was essential for every warrior, and more horses meant faster movement and greater endurance during campaigns. The grass grew thick enough to support massive herds that fueled the cavalry. Without this environmental window, the initial expansion might have stalled before it began. Tribes like the Merkits, Tatars, Keraites, Turks, Naimans, and Mongols fell under one command after decades of conflict. Buddhist Uyghurs of Qocho surrendered voluntarily and joined the new empire. Genghis Khan then turned his attention to the Qara Khitai and the Khwarazmian Empire. His early victories relied on mobility rather than siege engines or heavy infantry. The steppe environment dictated the rhythm of war, with most conquests occurring during warmer seasons when grazing was sufficient.
Every city that resisted the Mongols faced total destruction in Central Asia. After the fall of Urgench, each soldier in an army of perhaps two tumens had a quota to execute twenty-four people. This math resulted in nearly half a million deaths within that single force alone. Large areas of Islamic Central Asia and northeastern Persia became seriously depopulated as a direct result. The Mongols used divide-and-conquer tactics against the Alans and Cumans by first warning the Cumans to end their support of the Alans. They defeated the Alans and then rounded on the Cumans who fled to Hungary for refuge. Some Alans were recruited into the Mongol forces and known as the Asud. One unit called Right Alan Guard combined with recently surrendered soldiers to fight alongside the invaders. A Chinese military colony led by general Qi Kongzhi was established in Besh Balikh. The decentralized Kipchaks only converted to Islam after the Mongol conquest unlike earlier centralized entities. The resulting merged society formed a Mongol ruling class over a Kipchak-speaking populace known as Tatar. This group eventually absorbed Armenians, Italians, Greeks, and Crimean Goths in Crimea.
The siege of Baghdad in 1258 ended five hundred years of Islamic power centered there. Hulagu Khan led one thousand North Chinese engineer squads during his conquest of the Middle East. These engineers brought advanced siege technology that allowed the Mongols to breach city walls previously considered impenetrable. Raids reached southwards into Palestine as far as Gaza in 1260 and again in 1300. The Battle of Ain Jalut in southeastern Galilee in 1260 marked the first decisive defeat for the Mongols. Muslim Bahri Mamluks halted their advance at this location. Most of the Mamluk military was composed of Kipchaks who had fled the initial invasions. The Golden Horde's supply of Kipchak fighters replenished these armies and helped them fight off the Mongols. The Mongols conquered areas including present-day Iran, Iraq, the Caucasus, and parts of Syria and Turkey. Voluntary surrender often replaced battle when cities realized resistance meant annihilation. The decentralized nature of the region made it vulnerable to rapid cavalry strikes. Trade routes through Central Asia were disrupted or destroyed by the constant warfare. The fall of Baghdad sent shockwaves through the Islamic world but did not stop the Mongol expansion entirely.
Genghis Khan launched progressive invasions of China starting with subjugation of the Western Xia in 1209. They destroyed the Western Xia completely in 1227 before defeating the Jin dynasty in 1234. The Song dynasty fell finally in 1279 after decades of fighting. Kublai Khan established the Yuan dynasty in China in 1271 as his greatest triumph. He created a Han Army out of defected Jin troops and an army called Newly Submitted Army from defected Song soldiers. The force invading southern China was far greater than any sent to invade the Middle East in 1256. Korea became a semi-autonomous vassal state of the Yuan dynasty for about eighty years. Nine separate invasions forced Goryeo to capitulate despite fierce local resistance. Attempts to invade Japan failed because fleets were scattered by kamikaze storms. The Kingdom of Dali became a vassal state in 1253 after King Duan Xingzhi defected to the Mongols. This defection helped them conquer the rest of Yunnan. The Mongols also invaded Sakhalin Island between 1264 and 1308. A Bureau of Buddhist and Tibetan Affairs governed Tibet which was conquered and put under Yuan rule.
Over three years from 1237 to 1240, the Mongols razed all major cities of Russia except Novgorod and Pskov. They destroyed Volga Bulgaria and Kievan Rus before moving into Poland, Bulgaria, Hungary, and other territories. Giovanni da Pian del Carpine traveled through Kiev in February 1246 as the Pope's envoy to the Great Khan. He wrote that word of the Mongol hordes spread terror and panic across Eastern Europe. The violent character of the invasions acted as a catalyst for further violence between European elites. This increase in violence correlates with a decrease in elite numerical skills according to some historians. The campaigns displaced populations on a scale never seen before in Central Asia or Eastern Europe. The Mongols withdrew from Eastern Europe after the death of Ögedei Khan in 1241. Their retreat allowed surviving states like Poland and Hungary to rebuild their defenses. Stone castles such as Spiš Castle in Slovakia were constructed later due to the threat of invasion. The Golden Horde continued to rule parts of Eastern Europe for centuries after the initial withdrawal. Conflict between Mongols and Eastern European polities persisted long after the main campaigns ended.
Kublai Khan's Yuan dynasty invaded Burma between 1277 and 1287 resulting in capitulation of the Pagan Kingdom. An invasion in 1301 was repulsed by the Burmese Myinsaing Kingdom. The Mongol invasions of Vietnam and Java resulted in defeat for the Mongol forces. Much of Southeast Asia agreed to pay tribute to avoid further bloodshed despite these failures. The Mongol invasions played an indirect role in establishing major Tai states in the region. Recently migrated Tais originally came from Southern China during the early centuries of the second millennium. Major Tai states such as Lan Na, Sukhothai, and Lan Xang appeared around this time. These new political entities emerged partly because the Mongol presence disrupted existing power structures. The failure to conquer Japan and Vietnam showed limits to Mongol naval capabilities. They relied heavily on cavalry which struggled in tropical environments and dense jungles. Tributary relationships allowed some regions to maintain autonomy while acknowledging Mongol supremacy. This strategy preserved resources for future campaigns elsewhere in Eurasia.
Estimates suggest that between twenty and sixty million people were killed between 1206 and 1405 during various campaigns. These figures exclude mortality from the Black Death in Europe, West Asia, or China. Contemporary records lack precision so estimates vary considerably among historians. Campaigns involved battles, sieges, early biological warfare, and massacres that devastated entire regions. Chinese censuses used to base these estimates are considered unreliable by modern scholars. Nevertheless, the campaigns killed a large number of people across Eurasia. The Mongol Empire became the largest contiguous land empire of all time at its height. It stretched from the Pacific to Central Europe covering areas now part of many countries. Historians regard the Mongol devastation as one of the deadliest episodes in human history. The demographic collapse had long-term effects on population distribution and economic development. Trade routes shifted as cities were destroyed and rebuilt under new rulers. The scale of loss remains difficult to quantify accurately due to missing data.
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Common questions
When did Temujin become Genghis Khan and unite the Mongol tribes?
Temujin became Genghis Khan in 1206, uniting warring Mongol tribes into a single force. This unification followed fifteen years of unusually wet and warm weather from 1211 to 1225 that allowed horses to breed in unprecedented numbers.
How many people died during the fall of Urgench under the Mongol Empire?
Nearly half a million deaths occurred within a single army of perhaps two tumens after the fall of Urgench. Each soldier had a quota to execute twenty-four people, resulting in total destruction for resisting cities in Central Asia.
What caused the first decisive defeat for the Mongols at the Battle of Ain Jalut?
The Muslim Bahri Mamluks halted the Mongol advance at the Battle of Ain Jalut in southeastern Galilee on the 4th of April 1260. Most of the Mamluk military was composed of Kipchaks who had fled the initial invasions and were replenished by the Golden Horde.
Which dynasty did Kublai Khan establish in China and when did it begin?
Kublai Khan established the Yuan dynasty in China in 1271 as his greatest triumph. The Song dynasty fell finally in 1279 after decades of fighting following the subjugation of the Western Xia in 1209.
When did the Mongols withdraw from Eastern Europe after their campaigns there?
The Mongols withdrew from Eastern Europe after the death of Ögedei Khan in 1241. Their retreat allowed surviving states like Poland and Hungary to rebuild their defenses against future threats.