What were the greatest empires in history?
Thirteen empires that made the world — presented as a collection, not a contest. No ranking, no verdict: from Achaemenid Persia to Imperial Japan, each in its own right.
Last updated: October 2026
Thirteen empires. No ranking, no winners — the Bureau doesn't rank history. What follows is a collection: thirteen realms that bent the arc of the world, each told in its own right, arranged oldest to youngest.
There is no single league table of empires, because empires can be measured in different ways — and the answer changes with the measure. By land area, the British Empire was the largest in history, covering roughly a quarter of the earth's land surface at its height. By contiguous land, the Mongol Empire was the largest ever. By share of humanity, the Achaemenid Empire ruled nearly half the world's population. By longevity, the Roman and Ottoman empires each endured for more than half a millennium. By influence, the contest is open: Rome gave Europe its law and languages, the Abbasids carried Greek science into new centuries, the British spread English and parliamentary government across the globe.
What unites them is a pattern. Empires rise when a state solves a problem of organisation — a new army, a new bureaucracy, a new way to move goods and ideas — and fall when that solution stops working, or when the cost of holding distant lands exceeds the benefit. This entry surveys the greatest of them in roughly chronological order, asking of each not just how big it was, but what it left behind.
The first true world empire was Persian. Cyrus the Great founded it around 550 BCE, and his successors ruled from India to the Balkans, governing perhaps 44 per cent of the world's population — a share no later empire has matched. The Achaemenids built the Royal Road, standardised coinage and taxation, dug a canal between the Nile and the Red Sea, and administered through satraps, provincial governors, checked by royal inspectors. Their policy of tolerating local religions and customs made a vast diversity governable. Alexander the Great destroyed the empire, but its administrative model echoed through every empire that followed.
No empire has left a deeper imprint on the modern world than Rome. From a city-state on the Tiber, Rome built a Mediterranean empire of perhaps five million square kilometres and some fifty to seventy million people, bound by roads, law and citizenship. Roman law is the ancestor of the civil-law systems of continental Europe, Latin America and much of Africa; the Romance languages — French, Spanish, Italian, Portuguese, Romanian — are Latin's descendants. The western empire fell in the fifth century CE, but the eastern, Byzantine half endured until 1453, and the idea of Rome haunted European politics for a thousand years after. The very word "emperor" derives from the Roman title imperator.
The Han dynasty (206 BCE – 220 CE) built a Chinese empire of comparable scale to Rome's, with a bureaucracy chosen increasingly by merit, a state Confucian ideology, and the Silk Road reaching westward to Persia and Rome. Han institutions — the civil service, the written standard, the idea of a unified China — shaped every later Chinese dynasty, and the name Han remains the identity of China's majority people. Centuries later, the Islamic caliphates carried a different kind of empire: the Umayyad caliphate at its height stretched from Spain to India, and the Abbasid caliphate made Baghdad the greatest city of its age, a centre of science, philosophy and trade where Greek, Persian and Indian learning were translated, debated and extended.
The Mongol Empire, founded by Genghis Khan, was the largest contiguous land empire in history — roughly twenty-four million square kilometres at its height, stretching from Korea to Hungary. Its conquests were devastating; its rule was transformative. The Pax Mongolica made the Silk Road safer than it had ever been, carrying goods, technologies, ideas and diseases across Eurasia. Gunpowder, printing and the plague all travelled the Mongol roads. The empire split into khanates — the Golden Horde in Russia, the Ilkhanate in Persia, the Yuan dynasty in China — and its legacy runs through the states that emerged from its wreckage, from Russia to Iran to China.
The Ottoman Empire, born around 1299, endured for more than six centuries, ruling at its height the Balkans, Anatolia, the Levant, Egypt, North Africa and much of Arabia. Its millet system let religious communities govern their own family law, and its capital, Constantinople, was among the world's greatest cities. The Spanish Empire, built on conquest in the Americas and silver from Potosí and Zacatecas, was the first empire on which, in the phrase of the age, the sun never set. Its legacy is a Spanish-speaking world of more than twenty countries, and a Columbian exchange of crops, animals, diseases and peoples that remade the planet's ecology.
The British Empire was the largest in history by land and population: at its height, around 1920, it covered roughly 35 million square kilometres and ruled more than 400 million people, about a fifth of humanity. Built on naval power, finance and industrial might, it spread the English language, parliamentary institutions, common law and the sport of cricket across the globe. It also spread famine, racism, extraction and war; its history is argued over fiercely in the countries it ruled and in Britain itself. Its dissolution after the Second World War — India in 1947, then the great wave of decolonisation — produced the Commonwealth, the English-speaking world's institutions, and a global language spoken by more than a billion people.
The greatest empires are not remembered for their maps. They are remembered for what survived their fall: languages and laws, religions and roads, cuisines and calendars, the borders they drew and the grievances they left. Every empire in this survey was both a machine of domination and a carrier of exchange — and that duality is why they remain so contested. To study empires is to study how the world became connected, and at what cost. The age of territorial empire is over; the questions empires raised — who rules, who benefits, who decides — are not.
Any survey of great empires must reckon with Russia. The Russian Empire, which grew from the Grand Duchy of Moscow from the sixteenth century onward, became by the nineteenth century the third-largest empire in history by land area, stretching from Poland to Alaska and from the Arctic to Central Asia. Unlike the sea empires, Russia expanded overland, absorbing Siberia, the Caucasus and Central Asia in a slow, centuries-long advance. Its legacy is the largest country on earth, and the borders and frozen conflicts of the post-Soviet space. The comparison with the maritime empires is instructive: where Britain ruled distant colonies that could be shed, Russia's empire was contiguous — and its collapse in 1917, and again in 1991, became a domestic upheaval rather than a distant withdrawal.
- Paul Kennedy, The Rise and Fall of the Great Powers.
- John Darwin, After Tamerlane: The Rise and Fall of Global Empires, 1400–2000.
- Peter Frankopan, The Silk Roads.
- Taagepera, Rein, "Size and Duration of Empires" (1978) — comparative data on imperial extent.
- Encyclopaedia Britannica entries on the Achaemenid, Roman, Mongol, Ottoman and British empires.