Unlike former sociological theories, which presented general models of social change with particular focus at the societal level, world-systems theory (or world system perspective) explores the role and relationships between societies (and the subsequent changes produced by them). A theory primarily developed by Immanuel Wallerstein, Samir Amin, Giovanni Arrighi and Andre Gunder Frank in response to the many new activities in the capitalist world-economy during the mid 1970s, world-systems theory is derived from two key intellectual sources, the neo-Marxist literature on development and the French Annales School and Fernand Braudel.
In Wallerstein's 1987 publication, World-System Analysis, he proclaims that world-systems theory is "a protest against the way in which social scientific inquiry is structured for all of us at its inception in the middle of the nineteenth century." He goes on to criticize the prevailing conception of dependency theory, and argues that the world is much too complicated to be classified as a bimodal system, a system with only cores and peripheries. It is in this light that one of the main tenets of world-systems theory appeared, the belief in the semi-periphery, which created a tri-modal system consisting of the core, semi-periphery, and periphery.
There are many ways to attribute a specific country to the core, semi-periphery, or periphery. Using an empirically-based sharp formal definition of "domination" in a two-country relationship, Piana in 2004 defined the "core" as made up of "free countries" dominating others without being dominated, the "periphery" as the countries which are dominated, and "semi-periphery" as the countries which are dominated (usuallybut not necessarilyby core countries) while at the same time they dominate others (usually in the periphery).