The Dawn of Civilization: Metal Trade and the Rise of Hierarchy

In the latter half of the fourth millennium BC, our ancestors witnessed a remarkable transformation, progressing from simple agrarian villages to complex urban civilizations. In regions as far apart as the Nile Valley, Mesopotamia, Central Asia, and the Indus Valley, the first states appeared together with writing, cities with populations exceeding 10,000, and unprecedented socio-economic inequalities. The cause of this "Urban Revolution" remains unclear. We present new empirical evidence suggesting that the discovery of bronze and the ensuing long-distance trade played a crucial role. Using novel panel data and 2SLS techniques, we demonstrate that trade corridors linking metal mines to fertile lands were more likely to experience the Urban Revolution. We propose that transit bottlenecks facilitated the emergence of a new taxing elite. We formally test this appropriability theory and provide several case studies in support.