The shi, or “knights,” were not a coherent class during the Warring States period, though figures identified as such were central to the social, political, and cultural dynamism of the era. As the fragmentary states of the early Zhou era politically consolidated, the nature of the aristocracy changed. The aristocracy bifurcated into a steeply divergent populace of “kings” and their kin at the top and the mass of undifferentiated knights far below. Although not exactly a period of shi ascendancy, it was, at the individual level, a time of very fluid social mobility. State governments grew in power to the point of being able to determine the power and status even of hereditary aristocrats. All social positions became gauged in relation to their utility for the state. Low-born knights could rise to positions of high power and status through meritorious service to the state. Diplomacy became a field in which talents for strategy or rhetoric could earn great merit. Some of the most influential figures of the Warring States were humble knights that distinguished themselves as diplomats. Social fluidity was likewise embodied in urbanization. As the Warring States saw rapid population growth, technological advancement, and economic specialization cities grew in size and changed in character. Where they had once been principally military and cult centers, they evolved into centers of commerce and manufacturing in which new communities and social institutions took shape.