Richman, Poorman, Beggarman, Chief: The Dynamics of Social Inequality

In summary, then, the circumscription theory in its elaborated form goes far toward accounting for the origin of the state. It explains why states arose where they did, and why they failed to arise elsewhere. It shows the state to be a predictable response to certain specific cultural, demographic, and ecological conditions. Thus, it helps to elucidate what was undoubtedly the most important single step ever taken in the political evolution of mankind.