World-systems theory (also known as world-systems analysis or the world-systems perspective), a multidisciplinary, macro-scale approach to world history and social change, emphasizes the world-system (and not nation states) as the primary (but not exclusive) unit of social analysis."World-system" refers to the inter-regional and transnational division of labor, which divides the world into core countries, semi-periphery countries, and the periphery countries.