The Largest Empires in History: The One Where the Sun Never Set

The largest empire in history by land area was the British Empire, covering about 35.5 million square kilometres — roughly a quarter of the world's land — at its height around 1920. It was so geographically scattered that the sun was always up somewhere within it, which is where the old boast came from. But "largest empire" is not one question; it is at least three, and each one crowns a different winner. By connected territory, a horseback army from the Mongolian steppe beats a navy that ruled the seas. By share of every human alive at the time, a Persian king from 2,500 years ago may beat them both. This is the full ranking, the mechanics of how each empire got that big, and the reason every one of them eventually stopped growing.

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The Short Answer: Largest Empires by Land Area

Rank	Empire	Peak Area (approx.)	Peak Era	Note
1	British Empire	35.5 million km²	~1920	Largest ever; scattered across every inhabited continent
2	Mongol Empire	24 million km²	~1270–1309	Largest contiguous land empire
3	Russian Empire	22.8 million km²	~1895	Largest contiguous empire to survive into the modern era
4	Qing Dynasty (China)	14.7 million km²	~1790	Largest empire in East Asian history
5	Spanish Empire	13.7 million km²	~1810	First truly global, transoceanic empire
6	French Colonial Empire	11.5 million km²	~1920 (second phase)	Concentrated in Africa and Southeast Asia
7	Abbasid Caliphate	11.1 million km²	~750 CE	Stretched from Central Asia to North Africa
8	Umayyad Caliphate	11 million km²	~720 CE	Fastest early Islamic expansion, Spain to India
9	Yuan Dynasty (China)	11 million km²	~1310	The Mongol successor state that ruled China
10	Portuguese Empire	10.4 million km²	~1815	Longest-lived European colonial empire (over 500 years)

Table: The ten largest empires in recorded history, ranked by peak land area. Estimates follow the standard reference for historical empire size, political scientist Rein Taagepera's growth-and-decline data on empires, cross-checked against Encyclopædia Britannica's entries for each state.

Area is the usual headline measure, but it rewards empires that grabbed sparsely populated land — deserts, tundra, steppe — which is why the ranking flips almost entirely when you count people instead of square kilometres. It also rewards maritime empires that could claim huge, thinly governed colonial territories without ever needing to physically hold every square kilometre of them at once, which is a very different achievement from marching an army across a continent.

The Mongol Empire's core conquests, from Genghis Khan's unification of the steppe tribes around 1206 to the empire's territorial peak a few decades later, added more land than the Roman Empire acquired in roughly four centuries of continuous expansion. Rome's empire, at its own peak under Trajan in 117 CE, covered about 5 million km² — a fifth the size of what the Mongols assembled starting from almost nothing.

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The British Empire: Largest by Area, but Never in One Piece

The British Empire earned the top spot because it was fundamentally a maritime empire: a global network of colonies, protectorates, dominions, and trading posts on every inhabited continent, connected not by roads or a shared border but by the world's dominant navy and merchant fleet. India, Canada, Australia, large parts of Africa, swaths of the Caribbean, and hundreds of islands across the Pacific and Indian Oceans together gave Britain about a quarter of Earth's land surface and, at its peak, somewhere between a fifth and a quarter of the world's population.

That structure is what makes the British Empire unique among the entries on this list. Every other empire in the top five — Mongol, Russian, Qing, Spanish — built its size mostly through land campaigns, expanding outward from a central territory until geography or an enemy stopped it. Britain, by contrast, never needed its territories to touch. A colony in the Caribbean and a protectorate in East Africa could both answer to London without ever sharing a land border, because the connective tissue was shipping lanes and naval bases, not roads.

The famous line that "the sun never sets on the British Empire" was, for a stretch of decades, literally accurate. Britain's territories spanned so many time zones — Canada in the west, Hong Kong and Australia in the east, colonies scattered across every ocean in between — that daylight was always falling on some part of the empire, even as it went dark over London itself. It is a nice piece of imperial branding, but it also describes a genuine structural fact: no single sunrise or sunset event could ever touch the whole empire at once.

That same geographic dispersal, though, was the empire's core weakness. A contiguous land empire can, in principle, be governed by moving officials and soldiers overland, however slowly. A scattered maritime empire depends entirely on ships, ports, and the ability to project naval power to wherever trouble breaks out — and once that naval and economic dominance eroded after two world wars, the empire unraveled with startling speed. India became independent in 1947. Within three decades, the vast majority of Britain's formal colonial holdings had become sovereign states. An empire that took roughly three centuries to build came apart in about thirty years.

How big was the British Empire at its actual peak?

The British Empire's largest extent, roughly 35.5 million km², occurred around 1920, shortly after World War I, when Britain absorbed former German and Ottoman territories as League of Nations mandates. That is nearly a quarter of all land on Earth and about 158 times the size of Great Britain itself.

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The Mongol Empire: Largest Contiguous Land Empire

If you tighten the definition to require an empire to be one unbroken stretch of territory — no oceans, no separate colonies, just a connected landmass you could theoretically walk across without leaving imperial soil — the record belongs to the Mongol Empire of the 13th century. At its peak around 1270–1309, it covered roughly 24 million km², stretching from the Sea of Japan and the Korean peninsula in the east to Eastern Europe and the edge of the Hungarian plain in the west, and from Siberia in the north down to the Persian Gulf and the edges of the Indian subcontinent in the south.

What makes the Mongol Empire the most startling entry on this entire list is not just its size, but the speed at which it was built. Genghis Khan unified the fractious, warring tribes of the Mongolian steppe into a single fighting force around 1206. From that starting point, in roughly six decades — much of it within Genghis Khan's own lifetime and the reigns of his immediate sons and grandsons — the Mongols conquered the Jin dynasty in northern China, the Khwarazmian Empire across Central Asia and Persia, the Kievan Rus principalities, and pushed raiding armies as far west as Poland and Hungary. No other empire on this list, and arguably no empire in recorded history, expanded that much territory that quickly.

Three factors made it possible, and each is worth unpacking because they reappear, in different forms, in every large empire that follows.

Mobility. Mongol horsemen could travel far greater distances per day than any contemporary army, using a relay system of remounts (each rider kept multiple horses and swapped them mid-journey) that let messages and troop movements outrun anything an enemy could organize in response. Think of it as the 13th-century version of a logistics network: not a single fast horse, but a whole relay system built for speed at scale, similar in spirit to how a modern shipping company beats a single delivery truck not through raw speed but through a coordinated network.

Organization. The Mongol military was structured on a decimal system — units of ten, a hundred, a thousand, and ten thousand — with promotion based on demonstrated competence rather than birth. That meritocratic structure is a genuine outlier for the era; most 13th-century armies were built around aristocratic lineage, not battlefield performance.

Psychological warfare and calculated brutality. Cities that surrendered without a fight were often spared and absorbed into the administrative system; cities that resisted were made deliberate examples of, with the news of that destruction spread ahead of the army by deserters and refugees. That reputation did real strategic work: several cities surrendered without a siege simply because the alternative had already been demonstrated elsewhere.

The empire's very size, though, became the seed of its collapse. No pre-modern communication or transportation system — no matter how good the horse relay was — could keep a landmass that large under one unified command indefinitely. After the death of Möngke Khan in 1259, the empire split into four increasingly independent khanates: the Golden Horde in the west, the Ilkhanate in Persia and the Middle East, the Chagatai Khanate in Central Asia, and the Yuan dynasty in China and Mongolia proper. They shared a founding dynasty and, for a while, cordial relations, but they governed and fought as separate states.

This split between "largest overall" and "largest contiguous" is a recurring pattern in world-record territory more generally — the same fork shows up in the tallest buildings in the world, where "tallest building" and "tallest freestanding structure" have produced different champions depending on which category a tower's spire technically counts toward.

Why is the Mongol Empire considered the most impressive by many historians, even though it's smaller than the British Empire?

The British Empire took roughly three centuries and the resources of an industrializing global naval power to reach 35.5 million km². The Mongol Empire reached 24 million km² in about six decades, starting from a collection of nomadic tribes with no cities, no navy, and no gunpowder weapons — using horses, discipline, and terror as its primary tools of conquest.

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The Russian Empire: The Contiguous Giant That Outlasted the Mongols

Third on the list, and worth its own section because it directly inherited part of the Mongol legacy, is the Russian Empire, which reached about 22.8 million km² around 1895 under the Romanov dynasty. Unlike Britain's overseas colonies, Russia's empire grew almost entirely by land, pushing east across Siberia to the Pacific and south into the Caucasus and Central Asia over roughly three and a half centuries, from the 16th century through the late 19th.

Russia's expansion east across Siberia is one of history's more underappreciated feats of territorial acquisition, largely because it happened without the dramatic set-piece battles that define the Mongol or British stories. Cossack explorers and fur traders pushed steadily eastward through the 1600s, reaching the Pacific coast by the mid-17th century — a westward-to-eastward crossing of roughly 8,000 km through terrain that included some of the coldest inhabited regions on Earth. That expansion was driven less by conquest of large existing states, since much of Siberia was sparsely populated, and more by the simple economics of the fur trade, which made claiming enormous tracts of frozen wilderness commercially worthwhile even at a low population density.

What distinguishes Russia's empire from Britain's and the Mongols' is continuity. Russia's territorial core is largely still intact today, first as the Soviet Union and now as the Russian Federation, which remains the largest single country in the world by area. Compare that to the British and Mongol Empires, both of which fragmented into dozens of independent states within a few generations of reaching their peaks. For more on how modern national borders trace back to exactly this kind of imperial-era land acquisition, see the largest countries in the world, where Russia's 17.1 million km² today is still nearly twice the size of second-place Canada.

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The Rest of the Top Ten: Caliphates, Dynasties, and Colonial Empires

The empires ranked four through ten on the table above rarely get the same pop-history treatment as the British or Mongol Empires, but each represents a genuinely different model of how a state gets very, very big.

The Qing Dynasty, China's last imperial dynasty, reached roughly 14.7 million km² around 1790 by absorbing Mongolia, Tibet, Xinjiang, and Taiwan into a Manchu-led state that already included the historical Chinese heartland. It stands as the largest empire in East Asian history and, unlike most entries on this list, ruled a population that was itself already enormous — China's population was well into the hundreds of millions even before the Qing conquests began.

The Spanish Empire, at roughly 13.7 million km² around 1810, was arguably history's first genuinely global, transoceanic empire — holding territory across the Americas, the Philippines, and parts of Europe and Africa simultaneously, connected entirely by sail. It set the template that the British Empire would later scale up: colonial holdings that never touch, held together by naval logistics rather than a shared land border.

The French Colonial Empire, in its second phase after 1830, reached about 11.5 million km² by around 1920, concentrated heavily in West and North Africa along with Indochina — a footprint shaped less by earlier conquest and more by the 19th-century "Scramble for Africa," in which European powers formally partitioned the African continent among themselves at the 1884–85 Berlin Conference.

The Abbasid and Umayyad Caliphates, at roughly 11.1 million km² and 11 million km² respectively, represent the two great waves of early Islamic expansion. The Umayyads, expanding out of the Arabian Peninsula starting in 661 CE, reached from the Iberian Peninsula in the west to the Indus River valley in the east within about six decades — a speed of territorial acquisition rivaled among pre-modern empires only by the Mongols. The Abbasids, who overthrew the Umayyads in 750 CE, held a somewhat smaller but more centrally organized realm from their capital in Baghdad, presiding over what is often called the Islamic Golden Age of science, mathematics, and translation.

The Yuan Dynasty, at about 11 million km², was the Mongol successor state that ruled China itself, founded by Kublai Khan — a reminder that "the Mongol Empire" on the earlier table is really a snapshot of the united empire before it split into the Yuan, the Golden Horde, the Ilkhanate, and the Chagatai Khanate.

The Portuguese Empire rounds out the top ten at roughly 10.4 million km² around 1815, notable less for peak size than for longevity: Portugal held overseas territory, in one form or another, for over five centuries — from its first outposts in the 15th century until Macau reverted to China in 1999, making it the longest-lived European colonial empire by a wide margin.

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Area vs. Population vs. Share of Humanity

"Largest" changes hands entirely depending on which yardstick you use:

• By area: British Empire, about 35.5 million km².
• By contiguous area: Mongol Empire, about 24 million km².
• By share of world population: The Achaemenid (Persian) Empire around 480 BC, which according to Guinness World Records' figures ruled approximately 44% of all humans alive at the time — around 49.4 million people out of an estimated global population of 112.4 million.

That third figure deserves unpacking, because it is genuinely the most striking statistic in this entire subject, and it is also the most counterintuitive. The Achaemenid Empire, founded by Cyrus the Great and expanded by his successors, stretched from the Balkans and Egypt in the west to the Indus Valley in the east — large by ancient standards, at somewhere around 5.5 million km², but nowhere close to the British Empire's 35.5 million km² and nowhere near the Mongol Empire's 24 million km² either. It doesn't crack the top ten by area at all. Yet by the far more human measure of "what fraction of every person alive on Earth did this state govern," it may be the most dominant empire that has ever existed.

The Achaemenid Persian Empire around 480 BC may have ruled close to 44% of the entire human species — the highest documented share in history. The British Empire, at its own 20th-century peak, ruled roughly 20–24% of world population in absolute terms of hundreds of millions of people, but a smaller *share* of a vastly larger global population.

The reason for the gap is arithmetic, not achievement. In 480 BC, the entire world population is estimated at roughly 112 million people — smaller than the population of a single modern mid-sized country like Mexico or Ethiopia today. Ruling 44% of that meant governing a few tens of millions of people, spread across a handful of major population centers in Egypt, Mesopotamia, and the Iranian plateau. By 1900, when the British Empire was near its peak, global population had grown to roughly 1.6–1.7 billion. Ruling "only" 20–24% of that population still meant governing several hundred million individual human beings — vastly more people in absolute terms than the entire Achaemenid Empire ever touched, but a smaller slice of a much bigger pie.

This is the same statistical trap that shows up whenever you compare records across very different population baselines, similar to how a small country today can have a higher literacy rate than a much larger country did a century ago, simply because the underlying denominator (the whole population, or the whole world) has changed shape underneath the comparison. A modern empire with a billion subjects can, technically, rule a smaller fraction of humanity than an ancient empire with a few tens of millions, purely because the world got so much more crowded in between.

Which empire ruled the largest population in absolute numbers?

The British Empire, by a wide margin. At its peak around 1920, it governed somewhere between 400 and 470 million people across its colonies, dominions, and India alone — more human beings in absolute terms than any empire before it, even though that number represented a smaller share of the far larger global population of the early 20th century.

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What Made These Empires Possible

Despite being separated by continents and thousands of years, the largest empires in history share a small set of structural enablers. Strip away the specific weapons and dates, and the pattern repeats with almost mechanical regularity.

Mobility and logistics. Every empire on this list solved the same core problem: how do you move soldiers, tax revenue, and information faster than your rivals or your own rebellious provinces can react? The Mongols solved it with relay horses. The Romans solved it with an extraordinary road network, much of which is still visible or in use today. The British solved it with steamships, coaling stations, and eventually telegraph cables strung along the ocean floor. In every case, the empire's effective size was capped by how fast it could move things across its own territory, not by how much land it could physically claim.

Administrative organization. Conquering territory is the easy part, historically speaking; keeping it is what separates a raid from an empire. The Achaemenid Persians built the "Royal Road," a formal postal and administrative highway system stretching over 2,600 km from Sardis to Susa, along with a system of regional governors called satraps who answered to the central king but managed local affairs. The Romans built a bureaucracy sophisticated enough to survive the empire splitting east and west. The British built the Indian Civil Service, an administrative machine that ran the subcontinent with a comparatively tiny number of British officials by delegating heavily to local structures.

A decisive military or technological edge. Steppe cavalry mobility for the Mongols. Naval gunnery and, later, industrial-scale weapons production for the British. Iron discipline and standardized legionary equipment for the Romans. In every case, the edge eventually eroded as rivals adopted or matched the same technology or tactics — which is a large part of why no empire's dominance has ever proven permanent.

And every one of them shared the same eventual downfall: overextension. Historians and political scientists studying empire size, most notably Rein Taagepera's growth-and-decline research on historical empires, have found a remarkably consistent pattern: empires grow rapidly while conquest is cheap relative to the resources available, then plateau and decline once the marginal cost of holding the next province exceeds what that province returns in taxes, resources, or strategic value. Beyond a certain size, the empire is no longer expanding because it's strong; it's expanding because momentum hasn't caught up with the underlying math yet.

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What People Get Wrong About "Biggest Empire"

A few misconceptions come up constantly whenever this topic gets discussed, and they're worth clearing up directly.

"The Roman Empire must be one of the largest ever, because it's the most famous." Fame and size are almost unrelated here. Rome's peak territorial extent under Trajan in 117 CE was about 5 million km² — genuinely enormous for its era and one of the most influential states in human history, but not close to the top of this list by area. It doesn't crack the top ten. Rome's outsized reputation comes from its longevity (over a thousand years counting the Eastern Roman Empire's survival until 1453), its legal and linguistic legacy, and the sheer volume of surviving literature and architecture — not from raw territorial size.

"Bigger empire always means more powerful empire." Not necessarily, and not for long. The largest empires by area, almost without exception, include huge tracts of sparsely populated or difficult terrain — Siberian tundra for Russia, Central Asian steppe for the Mongols, Saharan and sub-Saharan territory for France. Controlling that land added to the map but didn't always add proportionally to tax revenue, manpower, or military capacity. A smaller, denser, better-organized empire can outcompete a larger, thinner one, which is part of why several empires on this list eventually lost wars to rivals that were smaller on paper.

"Empires collapse because of a single decisive defeat." Rarely true in isolation. Every major empire on this list declined over decades or centuries through a combination of overextension, succession crises, economic strain, and the slow erosion of whatever technological or organizational edge got them there in the first place. The Mongol Empire's split into rival khanates after 1259 wasn't caused by a lost battle; it was caused by an inheritance dispute compounded by the empire simply being too large to govern from one center. The British Empire's rapid post-1945 decolonization wasn't triggered by a single military loss either; it followed two exhausting world wars that drained the naval and economic dominance the whole system depended on.

"The largest empire and the largest country today are basically the same thing." They're related but distinct. Russia is both the largest country in the world today (about 17.1 million km²) and the modern-day successor to the third-largest empire in history (22.8 million km² at its imperial peak), but the two figures describe different eras and different political structures — one a sovereign nation-state, the other a multiethnic empire ruled by a monarchy. For the modern comparison, the largest countries in the world covers how today's national borders settled into their current shapes.

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Frequently Asked Questions

Q: What was the largest empire in history? A: By land area, the British Empire, which covered about 35.5 million km² — roughly a quarter of the world's land — at its peak around 1920. It was so geographically spread across the globe that the sun was always shining on some part of it, giving rise to the phrase "the empire on which the sun never sets."

Q: What was the largest contiguous empire? A: The Mongol Empire of the 13th century, at about 24 million km² of connected territory stretching from the Sea of Japan to Eastern Europe. The British Empire was larger overall but was a scattered, sea-linked network; the Mongol Empire was the largest single connected landmass ever ruled, and it was conquered within roughly one lifetime, starting from Genghis Khan's unification of the Mongol tribes in 1206.

Q: Which empire ruled the largest share of the world's population? A: Likely the Achaemenid (Persian) Empire around 480 BC, which according to Guinness World Records figures ruled close to 44% of all people then alive — the highest documented proportion in history. The British Empire ruled far more people in absolute numbers (several hundred million), but a smaller share, because the world population by 1900 was roughly fifteen times larger than it was in 480 BC.

Q: Why did the largest empires collapse? A: Overextension, in almost every case. Beyond a certain size, defending and administering distant frontiers costs more than they return in taxes, resources, or strategic value. Communication delays, succession disputes, local rebellions, and the expense of standing armies eventually overwhelm central control. The Mongol Empire fractured into four rival khanates after 1259; the British Empire decolonized rapidly after World War II once its naval and economic dominance had eroded.

Q: Was the Roman Empire one of the largest ever? A: It was vast and hugely influential — about 5 million km² at its peak under Trajan in 117 CE — but it does not rank among the ten largest empires by area; states like the British, Mongol, Russian, Qing, and Spanish empires were all considerably bigger. Rome's significance lies in its thousand-year-plus longevity, its legal system, and its lasting cultural and linguistic impact rather than sheer territorial size.

Q: How did the Mongols conquer so much land so quickly? A: A combination of horse-based mobility (relay systems that let messages and troops move faster than any rival army could react), a meritocratic decimal military organization that promoted based on performance rather than birth, and a calculated reputation for destroying any city that resisted, which caused many others to surrender without a fight. The result was roughly 24 million km² of conquest in about six decades, starting from a fractured collection of steppe tribes with no cities or navy of their own.

Q: What's the difference between the Mongol Empire and the Yuan Dynasty? A: The Mongol Empire refers to the united empire founded by Genghis Khan and expanded by his immediate successors, which peaked at roughly 24 million km² before splitting after 1259. The Yuan Dynasty was one of the four successor khanates, founded by Kublai Khan, that specifically ruled China and Mongolia — at roughly 11 million km², it was significant on its own but only about half the size of the empire it emerged from.

Q: Is Russia today the same size as the Russian Empire was? A: No — smaller. The Russian Empire reached about 22.8 million km² at its peak around 1895, including territory that later became independent countries such as Finland, Poland, Ukraine, and the Central Asian republics. Modern Russia covers about 17.1 million km², still the largest country in the world today, but roughly 5.7 million km² smaller than the empire's historical peak.

Q: What was the fastest-expanding empire relative to its starting size? A: The Mongol Empire is the strongest candidate, expanding from a collection of disunited steppe tribes with essentially no territory in 1206 to roughly 24 million km² within about six decades. The Umayyad Caliphate is a close second, expanding from the Arabian Peninsula to a realm stretching from Iberia to the Indus River valley — roughly 11 million km² — in a similarly short span after 661 CE.

Q: Does the United States count as an empire, and how would it rank? A: The United States has never held territory on the scale of the empires above; its total land area, including all 50 states, is about 9.8 million km², which would place it well outside the top ten historical empires by area even before accounting for the fact that it is a sovereign federal republic rather than an empire in the traditional sense. Some historians describe the post-1945 period of American military bases, alliances, and economic influence as a form of informal empire, but that is a structurally different phenomenon from direct territorial rule and isn't comparable on a land-area basis.

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The Takeaway

There is no single largest empire in history; there are three, and each one wins by refusing to answer the question the same way. The British Empire wins on raw land area because it was built by ships rather than armies, letting it claim territory on every continent without those territories ever needing to touch. The Mongol Empire wins on connected, contiguous conquest because it was built by horsemen who could move and organize faster than any 13th-century rival, assembling 24 million km² in roughly the length of one long human life. And the Achaemenid Persian Empire may win on the most human measure of all — the share of every person alive at the time who lived under its rule — precisely because the world it ruled was so much smaller than the ones the later empires inherited. Every one of these records eventually broke the same way, too: not through a single lost battle, but through the slow, unglamorous math of overextension, where the cost of holding the next province finally exceeded what it gave back.

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Read next:

• The Largest Countries in the World
• The Tallest Buildings in the World
• The Largest Structures Ever Built
• The Largest Islands in the World

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Sources

• Rein Taagepera, "Size and Duration of Empires: Growth-Decline Curves," Social Science History and related peer-reviewed empire-size datasets
• Encyclopædia Britannica — entries on the British Empire, Mongol Empire, Russian Empire, Qing Dynasty, Spanish Empire, Achaemenid Empire, Roman Empire, Umayyad and Abbasid Caliphates
• Guinness World Records — "Largest empire by percentage of world population" (Achaemenid Empire, ~44% of world population, 480 BC)
• Historical population-share and area estimates compiled from academic empire-size research (Taagepera datasets) and Britannica reference entries

Bottom line: The British Empire wins on area, the Mongols on connected land, and the Persians possibly on share of humanity — proof that even "the largest empire ever" has three different correct answers.

Last verified: July 2026