The world-system perspective emerged during the world revolution of 1968 when social scientists contemplated the meaning of Latin American dependency theory for Africa. Immanuel Wallerstein, Terence Hopkins, Samir Amin, Andre Gunder Frank, and Giovanni Arrighi developed slightly different versions of the world-system perspective in interaction with each other. The big idea was that the global system had a stratified structure on inequality based on institutionalized exploitation. This implied that the whole system was the proper unit of analysis, not national societies, and that development and underdevelopment had been structured by global power relations for centuries. The modern world-system is a self-contained entity based on a geographically differentiated division of labor and bound together by a world market. In Wallerstein’s version capitalism had become predominant in Europe and its peripheries in the long 16th century and had expanded and deepened in waves. The core states were able to concentrate the most profitable economic activities and they exploited the semi-peripheral and peripheral regions by means of colonialism and the emergent international division of labor, which relies on unequal exchange. The world-system analysts all focused on global inequalities, but their terminologies were somewhat different. Amin and Frank talked about center and periphery. Wallerstein proposed a three-tiered structure with an intermediate semiperiphery between the core and the periphery, and he used the term core to suggest a multicentric region containing a group of states rather than the term center, which implies a hierarchy with a single peak. When the world-system perspective emerged, the focus on the non-core (periphery and semiperiphery) was called Third Worldism. Current terminology refers to the Global North (the core) and the Global South (periphery and semiperiphery).