State formation is the process of the development of a centralized government structure in a situation in which one did not exist. State formation has been a study of many disciplines of the social sciences for a number of years, so much so that Jonathan Haas writes, "One of the favorite pastimes of social scientists over the course of the past century has been to theorize about the evolution of the world's great civilizations." The study of state formation is divided generally into the study of ancient state formation (those that developed in stateless societies), medieval or early modern state formation, and the study of modern state formation (particularly of the form that developed in Europe in the 17th century and spread around the world). State formation can include state-building and nation-building. Academic debate about various theories is a prominent feature in fields like anthropology, sociology, economics, and political science. Dominant frameworks emphasize the superiority of the state as an organization for waging war and extracting resources. Prominent theories for medieval, early modern, and modern state formation emphasize the roles of warfare, commerce, contracts, and cultural diffusion in ushering in the state as a dominant organizational form. State (polity) There is no academic consensus on the definition of the state. The term "state" refers to a set of different, but interrelated and often overlapping, theories about a certain range of political phenomena. According to Walter Scheidel, mainstream definitions of the state have the following in common: "centralized institutions that impose rules, and back them up by force, over a territorially circumscribed population; a distinction between the rulers and the ruled; and an element of autonomy, stability, and differentiation. These distinguish the state from less stable forms of organization, such as the exercise of chiefly power." The most commonly used definition is by Max Weber who describes the state as a compulsory political organization with a centralized government that maintains a monopoly of the legitimate use of force within a certain territory.