The Network Structure of the Urban Revolution

Abstract

Although long-distance interaction dates back to Prehistory, the scale and complexity of exchange during the Urban Revolution are unparalleled. How did early urban societies organize transcontinental trade without modern transportation, financial systems, or institutional infrastructures? To answer this, we formally analyze the Uruk Expansion in Chalcolithic Mesopotamia (~4000–3000 BCE), arguably the first episode of “globalization” in human history. Using network analysis on a new dataset of over 1,700 settlements and routes, we show that Uruk’s early river-based supply chains evolved through diaspora-driven bridging ties that generated small-world network structures, fostering integration and system-wide connectivity. This transformation—from dendritic to integrated networks—challenges dependency-based explanations and instead supports a market formation model of early urban exchange.