How Large Was the Largest Ancient Empire?

Ruins of Persepolis
Kaveh Kazemi/Getty Images

When referring to ancient/classical History, it's easy to lose sight of the fact that Rome wasn't the only country with an empire and that Augustus wasn't the only empire-builder. Anthropologist Carla Sinopoli says empires tend to be associated with single individuals, especially — among the ancient empires — Sargon of Akkad, Chin Shih-Huang of China, Asoka of India, and Augustus of the Roman Empire; however, there are many empires that are not so linked. Sinopoli builds a composite definition of an empire as a "territorially expansive and incorporative kind of state, involving relationships in which one state exercises control over other sociopolitical entities... The diverse polities and communities that constitute an empire typically retain some degree of autonomy. ..."

Which Was the Largest Empire in Antiquity?

The question here, though, is not what an empire is, although it's important to keep that in mind, but which and what size was the largest empire. Rein Taagepera, who has compiled useful stats for students on the duration and size of ancient empires, from 600 B.C. (elsewhere his stats date to 3000 B.C.) to 600 A.D., writes that in the ancient world, the Achaemenid Empire was the largest empire. This doesn't mean it had the most people or lasted longer than others; it just means it was at one time the ancient empire with the largest geographic area. For details on the calculation, you should read the article. At its height the Achaemenid Empire was larger than that of the empire-seizer Alexander the Great:

"A superimposition of the maps of Achaemenid and Alexander's empires shows a 90% match, except that Alexander's realm never reached the peak size of the Achaemenid realm. Alexander was not an empire-founder but an empire-seizer who arrested the decline of the Iranian empire for a few years."

At its greatest extent, in c. 500 B.C., the Achaemenid Empire, under Darius I, was 5.5 square megameters. Just as Alexander did for his empire, so the Achaemenids had earlier taken over the pre-existing Median empire. The Median Empire had reached its peak of 2.8 square megameters in about 585 B.C. — the largest empire to date, which the Achaemenids took less than a century to almost double.


  • "Size and Duration of Empires: Growth-Decline Curves, 600 B.C. to 600 A.D." Rein Taagepera. Social Science History Vol. 3, 115-138 (1979).
  • "The Archaeology of Empires." Carla M. Sinopoli. Annual Review of Anthropology, Vol. 23 (1994), pp. 159-180
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Gill, N.S. "How Large Was the Largest Ancient Empire?" ThoughtCo, Apr. 5, 2023, Gill, N.S. (2023, April 5). How Large Was the Largest Ancient Empire? Retrieved from Gill, N.S. "How Large Was the Largest Ancient Empire?" ThoughtCo. (accessed May 28, 2023).