Immanuel Wallerstein developed the modern world-system theory to describe the global economic system. He argued that the world system is characterized by the economic domination of core countries over semi-peripheral and peripheral countries. The core nations have the most powerful economies and export capital-intensive manufactured goods, while the peripheral nations export raw materials and agricultural goods. Semi-peripheral countries fall between the core and periphery in terms of economic power and specialize in some manufacturing. Wallerstein viewed the modern world system as a self-contained global economic system defined by the dominant economic relationships between core and peripheral states.