The textbook context clearly distinguishes between conditions, causes, and outcomes. Highly productive agriculture was necessary to support urban populations engaged in non-food activities. Water transport was essential as 'efficient transport is also important for urban development' and rivers were 'routes of goods transport.' The lack of local resources like metal and stone was a cause because it necessitated long-distance trade, which drove urbanisation. Division of labour is explicitly stated as 'a mark of urban life,' making it an outcome. Seals represent specialised craft production that emerged in cities. Military power of kings developed as 'small states' grew alongside cities.