An empire is a state that rules many peoples and lands from one centre. There have been dozens of empires, but only a few covered a noticeable share of the Earth's land. Area is a rough measure — ancient borders were fuzzy and historians' estimates differ by millions of square kilometres. Below are commonly cited estimates at each empire's greatest extent.
The largest empires by area: table
| Empire | Peak | Area, million km² | Share of land |
|---|---|---|---|
| British Colonial Empire | 1920 | ≈ 35.5 | ≈ 24% |
| Mongol Empire | 1270s | ≈ 24 | ≈ 16% |
| Russian Empire | 1895 | ≈ 22.8 | ≈ 15% |
| Union of Soviet Socialist Republics | 1945–1991 | ≈ 22.4 | ≈ 15% |
| Qing Dynasty | 1790 | ≈ 14.7 | ≈ 10% |
| Spanish Empire | 1810 | ≈ 13.7 | ≈ 9% |
| French colonial empire | 1920 | ≈ 11.5 | ≈ 8% |
| Umayyad Caliphate | 720 | ≈ 11 | ≈ 7% |
| Abbasid Caliphate | 750 | ≈ 11 | ≈ 7% |
| Yuan Dynasty | 1310 | ≈ 11 | ≈ 7% |
| Portuguese Empire | 1815 | ≈ 10.4 | ≈ 7% |
| Achaemenid Empire | 500 BC | ≈ 5.5 | ≈ 4% |
| Roman Empire | 117 | ≈ 5 | ≈ 3% |
Figures are rounded: estimates by different authors (Rein Taagepera, Peter Turchin and others) differ by 10–20%.
The British Empire: the largest empire in history
At its peak after World War I, the British Crown ruled almost a quarter of the world's land and population: Canada, Australia, India, much of Africa and islands in every ocean — "the empire on which the sun never sets". It was a maritime empire, held together by the navy and trade rather than a continuous land border. It dissolved between 1947 and the 1970s, from the Independence and Partition of India to the independence of the last African colonies.
The Mongol Empire: the largest contiguous empire
Counting only continuous territory, the Mongol Empire comes first. Within seventy years of Temüjin proclaimed Genghis Khan in 1206, the Mongols went from Korea to Hungary: the Mongol invasion of Rus', the Mongol sack of Baghdad, the conquest of China under Kublai Khan. By the 1260s the empire had split into four khanates — the Yuan Dynasty in China, the Golden Horde, the Ilkhanate in Persia and the Chagatai Khanate. The Mongol Empire on the globe
The Russian Empire and the USSR
The Russian Empire, proclaimed in 1721 (Proclamation of the Russian Empire), stretched from Poland to Alaska (sold in 1867) and covered about 22.8 million km² by the end of the 19th century — third in history. The USSR inherited almost the same territory. After the Dissolution of the Soviet Union, Russia remained the largest country in the world at about 17.1 million km².
Empires of the ancient world
Ancient empires look smaller in numbers but covered almost the whole known world of their time. The Achaemenid Empire, founded by Cyrus the Great, was the first empire stretching from Egypt and the Aegean to the Indus. The Roman Empire reached its greatest extent under Trajan in 117, turning the Mediterranean into an inland sea. At the same time, at the other end of Eurasia, the Han Dynasty was comparable to Rome in both area and population. The world in 117
Why large empires fell apart
- Distance. A messenger needed weeks to ride from Rome to Syria and months from Karakorum to Hungary. Governing the edges was hard and governors became independent.
- Inheritance. The Mongol and Carolingian empires were divided among heirs — the Treaty of Verdun in 843 split the Frankish realm in three.
- Nationalism. In the 19th and 20th centuries the peoples of empires demanded their own states, ending the Ottoman Empire, Austria-Hungary and the colonial empires.
A map of empires on the globe
On the Panchronia globe you can see each of these empires at its peak and follow how it grew and collapsed: move the timeline and the borders change year by year. Tap an empire to see its dates, capital and rulers.
Questions
What was the largest empire in history?
By area, the British Empire: about 35.5 million km² in 1920, almost a quarter of the Earth's land. The largest contiguous empire was the Mongol Empire, about 24 million km².
How big was the Roman Empire?
At its peak under Emperor Trajan in 117 AD, about 5 million km² — from Britain to Mesopotamia and from the Rhine to the Sahara.
Was the Mongol Empire bigger than the Roman Empire?
Yes, almost five times bigger: about 24 million km² against 5 million km² for Rome at its peak.