The document summarizes World Systems Theory, which views international migration as a result of disruptions caused by the expansion of global capitalism. According to the theory, as capitalist firms penetrate peripheral regions seeking land, resources and labor, they undermine traditional social structures and create rootless populations prone to migration. International migration patterns are explained not by wage differences but by historical world-system dynamics like colonialism that create social and economic ties between countries. The theory divides the global economy into core, semi-peripheral and peripheral states and views migration as a natural outcome of the unequal development perpetuated by the capitalist world-system.