A nonlinear dynamical model for the dynastic cycle

A three-class model of society (farmers, bandits and rulers) is considered in order to explain alternation between despotism and anarchy in ancient China. In the absence of authority, the dynamics of farmers and bandits are governed by the well-known prey-predator interactions. Rulers impose taxes on farmers and punish bandits by execution. Thus, farmers are a sort of renewable resource which is exploited both by bandits and by rulers. Assuming that the dynamics of rulers is slow compared with those of farmers and bandits, slow-fast limit cycles can be identified through a singular perturbation approach. This provides a possible explanation for the accomplishment of an endogenously generated dynastic cycle, i.e. a periodic switching of society between despotism and anarchy. Moreover, there is numerical evidence for the occurrence of a cascade of period-doubling bifurcations leading to chaotic behaviour.