The changes of recent years--economic interdependence, growth of regional and international organizations, and self-assertion on the part of new subgroups or transnational groups--have led many to speculate that the post-Westphalian system of sovereign states is fundamentally shifting. This intriguing book argues that nation-states and territorially sovereign powers were not the only possible form of organization, and that the end of the Middle Ages saw the flowering of a variety of alternatives, including the league of city-states and the independent city-state. The author argues that the latter two were superior to the feudal forms they replaced and coexisted for an extended period. The sovereign state won out against these rivals only later. The book shows the limitations in the realist assumption of an international order made up exclusively of nation-states. The author's argument against other progressive views of history seems overdone, however, since his own theory ends up with the same teleological result: the nation-state eventually won out against its rivals because it was superior. The question for the future is whether the world is sufficiently different that this margin of superiority is no longer decisive.