The pater compares prehistoric social complexity in two regions of the lower Yangtze River: the circum Lake Taihu area and the Ningbo-Shaoxing plains. It first defines social complexity as a progressive shift from egalitarian to hierarchical forms, shaped by factors such as population growth, surplus production, and elite-driven organization. In the Lake Taihu region, archaeological evidence suggests a steady trajectory from the Majiabang culture's small egalitarian villages to the Songze culture's early differentiation and the Liangzhu culture's emergence as a complex chiefdom, supported by intensified paddy agriculture, increasing population dencity, and rising social stratification in burials and settlement hierarchies. In constrast, the Ningbo-Shaoxing plains show more modest changes: communities remained relatively small and egalitarian since the Hemudu period, with little functional zoning or conspicous wealth. Only under later influence from the north did some signs of complexity appear, but on a much smaller scale than in the Lake Taihu region. These differences reflect how local environments, varied resource bases, and population pressures shaped diverging paths to complexity. Within the circum Lake Taihu region, surpluses from intensive rice farming fueled a feedback loop of increasing hierarchy, whereas the more fragmented landscape of the Ningbo-Shaoxing plains produced smaller, less complex societies, advacing chiefly through external stimuli.