The Merovingians inherited an urban network from the Roman Empire that remained substantially intact. Although Gallic cities had long been declining in extent and sophistication, during late antiquity their landscapes were adapted to contemporary priorities through the provision of walls and churches, and their politics was transformed by the emergence of bishops as leaders of urban communities. When the upper tiers of imperial administration disappeared, this equipped the vast majority of cities to survive as the basic building blocks of Merovingian kingdoms that were initially conceived as aggregations of city–territories. In ruling through their cities, the Merovingians expanded upon existing mechanisms for the extraction of taxes and services, while relying on centrally appointed bishops and counts rather than city councils for the projection of their authority. This generated fierce competition between kings for control of cities and among local elites for positions of power within them. In the later Merovingian period, however, the significance of cities diminished as stable territorial kingdoms emerged, political practice was centralized around the royal courts, and the Roman administrative legacy finally disintegrated. But the cities remained preeminent religious centers, and, with the beginnings of economic revival, continued to perform a range of functions unmatched by other categories of settlement.
A hierarchical urban network control with integration of demand balance and traffic signal coordination**This work is supported in part by the National Science Foundation of China (Grant No. 61433002, 61521063, 61374110, 61473288), the Beijing Natural Science Foundation (Grant No. 4142055), NSFC International Cooperation Project (Grant No. 71361130012).