In 376 CE, large numbers of Goths cross the Danube, seeking admission to the territory of the Roman Empire, a political institution which, despite having both new and longstanding systematic weaknesses, wields effective power across the lands surrounding the Mediterranean and beyond.

The Empire has large numbers of trained, supplied, and disciplined soldiers, it has a comprehensive civil administration based in thriving cities with effective control over public finances, and it maintains extreme differences of wealth and status including slavery on a large scale.

It has wide-ranging trade networks that allow even modest households to use goods made by professionals a long way away.

Among its literate elite, it has ideological legitimacy as the only worthwhile form of civilization, and a unity based on comprehensive familiarity with Greek and Roman literature and rhetoric.

By 476, when Odoacer deposes the Emperor Romulus, the Western Roman Empire wields negligible military, political, or financial power and has no effective control over the scattered Western domains that still describe themselves as Roman.

While its legitimacy lasts for centuries and its cultural influence remains today, the Western Empire never has the strength to rise again.The events of the decline are the subject of debate at the time, often with a strongly religious flavor.

Like the events surrounding the fall of the Roman Republic, much of this period is unusually well-documented, though there are very few figures that directly describe the strength of the economy, of the army, of the civil administration, or of the barbarians.

Modern historians nevertheless debate the relative importance of these and other factors, in particular, whether the state was significantly weaker by 376 than it had been in previous centuries, and why the West collapsed while the East did not.

The collapse, and the repeated attempts to reverse it, are major subjects of the historiography of the ancient world and they inform much modern discourse on state failure.