[A world-system is] a system that is a world and which can be, most often has been, located in an area less than the entire globe. World-systems analysis argues that the units of social reality within which we operate, whose rules constrain us, are for the most part such world-systems (other than the now extinct, small mini-systems that once existed on the earth). World-system analysis argues that there have been thus far only two varieties of world-systems: world-economies and world empires. A world-empire (examples, the Roman Empire, Han China) are large bureaucratic structures with a single political center and an axial division of labor, but multiple cultures. A world-economy is a large axial division of labor with multiple political centers and multiple cultures.