As a basis for comparison, Wallerstein proposes four different categories, core, semi-periphery, periphery, and external, into which all regions of the world can be placed. The categories describe each region's relative position within the world economy as well as certain internal political and economic characteristics.
Empires maintained specific political boundaries, within which they maintained control through an extensive bureaucracy and a standing army. Only the techniques of modern capitalism enabled the modern world economy, unlike earlier attempts, to extend beyond the political boundaries of any one empire.