Empires rarely follow a fixed expiration date, but many historians and popular analyses suggest that a typical “great” empire lasts roughly 200–300 years , with an often‑cited average around 250 years. That doesn’t mean every empire collapses exactly at 250; some crumble in a century, while a few stagger on for far longer.

A rough “rule of thumb”

A lot of the “250‑year” idea comes from British‑era writer Sir John Glubb, who studied 3,000 years of empires and argued that many go through similar life‑cycle stages—rise, conquest, comfort, apathy, decline—over about 250 years. Modern commentators sometimes repeat this as a rule‑of‑thumb, especially in discussions about the United States, which is now around 250 years old.

That said, historians also point out that there is no universal “average” because empires are defined differently, and their start/end dates are often fuzzy.

How long did famous empires last?

Here are a few well‑known examples, keeping in mind that scholars sometimes debate exact dates:

Empire / polity| Approximate duration| Notes
---|---|---
Achaemenid Persian| ~220 years| Founded by Cyrus the Great c. 550 BC; ended with Alexander’s conquest c. 330 BC. 3
Roman Empire (imperial phase)| ~500 years (West), ~1,000 years (East/Byzantine)| Western half fell c. 476 AD; Eastern (Byzantine) lasted until 1453. 13
Mongol Empire| ~160 years| Unified under Genghis Khan (1206); fragmented by mid‑14th century. 1
Ottoman Empire| ~624 years| 1299–1923; one of the longest‑lasting major empires. 1
British Empire| ~400 years| From early 17th‑century colonies to mid‑20th‑century decolonization. 1
Major Chinese dynasties (Tang, Ming, Qing)| ~200–300 years each| Often cited as “empire‑like” cycles. 1

These durations show how variability is the norm , not a strict 250‑year rule.

Why do empires usually fall?

Empires tend to weaken when several pressures stack up at once. Common patterns include:

  • Overextension : Governing distant territories becomes too costly and slow to respond to crises.
  • Economic strain : Declining tax revenue, inflation, or resource depletion erodes state capacity.
  • Internal decay : Corruption, elite infighting, and loss of public trust in institutions.
  • External threats : Rivals, invasions, or coalitions of enemies.
  • Cultural‑political shifts : New ideas, social movements, or identity politics that undermine imperial legitimacy.

Glubb‑style life‑cycle theories argue that empires often begin with energetic, outward‑looking founders and end with inward‑looking elites more focused on comfort than survival.

Is there a “trending” pattern?

Some modern analyses suggest that global dominance windows are getting shorter as technology, communication, and competition accelerate. In that view, even if an empire survives 250 years, its period of clear “world‑leading” power may be much briefer than in earlier eras.

So, to answer your headline question directly: Empires usually last a few centuries, often in the 200–300‑year range, but there is no iron‑clad rule—only a recurring pattern of rise, peak, and decline shaped by politics, economics, and culture.

Information gathered from public forums or data available on the internet and portrayed here.