Crisis of the Third Century (also known as the "Military Anarchy" or the "Imperial Crisis" ) is a commonly applied name for the crumbling and near collapse of the Roman Empire between 235 and 284 caused by the three simultaneous crises of external invasion, internal civil war and economic collapse. The changes in the institutions, society, economic life and eventually religion were so profound and fundamental, the "Crisis of the Third Century" is increasingly seen as the watershed marking the difference between the classical world and the early medieval world, or world of late antiquity.

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