The question is not why Bronze Age empires fell, but why nothing like them returned for centuries. The causes of the Bronze Age collapse are debated — droughts, the Sea Peoples, internal revolts. But a decisive factor was iron. While the tin required for bronze was concentrated in rare deposits and easily monopolized by imperial courts, iron is the 4th most abundant element in Earth’s crust. In contrast to bronze, iron democratized violence. Because iron could be produced locally, imperial centers permanently lost their monopoly on the tools of war, ending the centralized equilibrium that had sustained Bronze Age states for 1,000 years. worksinprogress.news