At 9 million square miles encompassing one-fifth of the Earth's total land mass, the Mongol Empire was the largest contiguous empire in the history of the world.
Public DomainThe Mongols swiftly rose to power in the 13th century — but their mighty empire fell almost as quickly as it came together.
In 1206, Genghis Khan became the ruler of all Mongols and began rapidly expanding his new territory. Within 73 years, it had become the largest contiguous empire in world history. But exactly how big was the Mongol Empire at its peak?
By 1279, the Mongol Empire stretched from the Sea of Japan in the east to present-day Poland in the west. The realm reached north into Russia and south into the Indian subcontinent. It covered an astonishing 28 modern-day countries.
But the Mongols’ power didn’t last long. Shortly after the death of Genghis Khan in 1227, civil war split his empire into four khanates. And as the years went on, the Mongol people abandoned their nomadic lifestyle, instead settling into the cities that they’d conquered.
They began to lose their cultural identity — and their military skills along with it. By 1368, all four khanates had begun to collapse. While the size of the Mongol Empire had astonished the world, it proved too large for its rulers to handle.
This is the story of how big the Mongol Empire was and how it ultimately fell apart.
The Growth Of Mongol Conqueror Genghis Khan’s Vast Domain
Genghis Khan, whose birth name was Temüjin, was the eldest child of a Mongol chieftain. He almost met his ruin at the young age of eight or nine, when his father died and his family was abandoned by their tribe.
Desperate to hold onto power, Temüjin killed his half-brother in 1180, seized control, and began defeating rival tribes. By 1206, he was the last ruler standing on the Mongolian steppe. He was subsequently awarded the title Genghis Khan and became the leader of all Mongols.
Public DomainGenghis Khan, the founder of the massive Mongol Empire.
Genghis Khan used this newfound authority to his advantage. He swiftly began conquering neighboring territories, expanding his empire across Asia. He sent his armies in all directions, indiscriminately invading any cities in his path.
As the size of the Mongol Empire grew, so did Genghis Khan’s power. He reformed various laws, established a merit-based government system, and embraced trade and religious freedom. These changes spawned increased loyalty among his subjects, further strengthening his hold on his realm.
The leader did hold onto some traditions, though. The Mongols’ nomadic lifestyle and skill on horseback contributed to their rapid spread across the continent. Their armies were mostly cavalry-based, allowing them to cover vast areas in a short period of time. And their use of bows and arrows made them well-suited to defeat enemies on the open plains of Eurasia.
Public DomainA 14th-century illustration of the Mongols’ siege of Baghdad in 1258.
Genghis Khan’s forces also adopted advanced military strategies for the time, such as psychological warfare. Before attacking a city, they would permit citizens to surrender voluntarily. If they agreed, they were folded into the Mongol Empire as subjects. If they resisted, they were slaughtered or enslaved. This ensured almost total loyalty.
As new territories were conquered, the Mongols embraced the innovations of their new subjects, leading to technological advancements such as stirrups, leather armor, and gunpowder, which helped keep them in power.
Eventually, Genghis Khan died in 1227, but the size of the Mongol Empire continued to grow under his descendants. And by 1279, it was the largest contiguous empire in world history.
How Big Was The Mongol Empire At Its Peak?
After Genghis Khan’s death, his son Ögedei took over as the second khan of the Mongol Empire. He was followed by his own son, Güyük, who was succeeded by another one of Genghis Khan’s grandsons, Möngke. Under Möngke’s leadership, the Mongols conquered parts of Iraq and Syria, expanding the size of the Mongol Empire to the west.
When Möngke died in 1259, power was supposed to transfer to his brother, Kublai Khan. However, his younger brother, Ariq Böke, seized his title while Kublai was traveling in China. Kublai Khan quickly returned to the Mongolian Plateau and defeated Ariq Böke in battle, forcing him to surrender.
Marco Polo visited Kublai Khan at his Xanadu estate in 1275 and wrote of his grand palace with rooms “completely covered with gold and silver and decorated in relief with pictures of dragons, birds, knights, scenes of battle, and various kinds of beasts… The hall is so vast and wide that more than 6,000 men could easily eat there.”
Less than a century after the rise of the Mongol Empire, its leaders had power and wealth beyond belief.
Public DomainMarco Polo wrote of his meeting with Kublai Khan in 1275.
Kublai Khan reigned from 1260 until his death in 1294, and under his rule, the size of the Mongol Empire reached its peak.
But exactly how big was the Mongol Empire at its height in 1279?
Officially, it covered at least 9 million square miles, but some historians believe that number might have been closer to 12 million square miles. This additional area was terrain that was influenced by the Mongols but may not have been officially conquered.
Either way, it was the largest contiguous empire in world history. Only the British Empire covered more land area — 13.7 million square miles — but its territories were scattered across the globe.
DannamEmpire/Wikimedia CommonsThe Mongol Empire at its greatest extent in 1279.
The Mongol Empire covered much of Eurasia, stretching across the entire Asian continent from east to west and even into parts of Eastern Europe. It encompassed all of modern Mongolia, North and South Korea, Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan, Turkmenistan, Afghanistan, Iran, Georgia, Armenia, and Azerbaijan.
The empire also controlled most of China, Ukraine, and Belarus, as well as parts of Russia, Turkey, Poland, Moldova, Romania, Syria, Iraq, Pakistan, and the northernmost bits of India, Myanmar, Laos, and Vietnam.
But despite the immense size of the Mongol Empire — or, perhaps, because of it — its khans wouldn’t stay in power for long.
The Fall Of The Largest Contiguous Empire In World History
Although the Mongol Empire reached its height under Kublai Khan, it also, at this same time, began to fall. The civil war that had brought him to power resulted in the fracturing of the empire into four separate khanates. Kublai Khan was technically the Great Khan of his realm, but his control was mostly limited to the Yuan dynasty that he established in China, Mongolia, and Korea.
The other three khanates were the Golden Horde of Eastern Europe, the Chagatai Khanate of Central Asia, and the Ilkhanate in Iran. By the time of Kublai Khan’s death in 1294, the khanates were effectively functioning as sovereign nations.
Public DomainThe Ilkhanate as depicted in the 14th-century Catalan Atlas.
The Ilkhanate was the first of the four to fall. It collapsed in the 1330s, partly due to the fact that roughly 30 percent of its population was killed by the Black Death. When its ruler succumbed to the illness in 1335, a succession crisis brought the khanate crashing down.
The Yuan dynasty was then defeated by China’s Ming dynasty in 1368. This date is considered the official fall of the Mongol Empire, though parts of the Golden Horde and Chagatai Khanate continued to exist for another century or two.
Why The Mongol Empire’s Size May Have Been Its Undoing
But what caused such a dramatic fall? Part of the struggle came from the size of the Mongol Empire. With separate khanates ruling large swaths of land across Eurasia, each area had different goals and needs.
GerritR/Wikimedia CommonsThe Mongols rose to power on the Mongolian steppe, but as they settled across the continent, they began to lose their influence.
There was also internal strife within each khanate. The Mongols and the people they’d conquered had disputes over whether to continue their traditional nomadic ways or adopt a more modern, sedentary lifestyle. What’s more, with the addition of a wide variety of civilizations, their own culture became diluted. As time went on, they began to lose their military prowess.
But while the empire fell as dramatically as it had risen, it left behind an astonishing legacy. The vast size of the Mongol Empire connected Europe and Asia like never before. During the Pax Mongolica, a period of peace and stability within the realm in the 13th and 14th centuries, the Silk Road was revived, allowing for the trade of goods between the continents.
So, how big was the Mongol Empire? In the end, too immense to last — but large enough to change world history forever.
After learning about the size of the Mongol Empire, discover how big the Roman Empire was at its peak. Then, discover how many children Genghis Khan really had.
