It is now taken for granted that the globe is divided into mutually exclusive territories, each of which belong to a particular community. To be a political community, it is thought, means to have sole possession of a piece of the Earth’s surface and to have complete authority over that land. Yet the history of political thought has little to tell us about when and how this conception arose. I argue that the first complete statement of this doctrine of the territorial state emerged with Emer de Vattel’s The Law of Nations in 1758. Vattel’s doctrine synthesized three ideas which had been developing in the genres of natural law and the law of nations since the Peace of Westphalia: the state was supreme over its territory; it possessed independent moral personality; and it was tied to a permanent human community. This dissertation recovers the ideological resources of territorial state formation by tracing the philosophical roots of these ideas in Samuel von Pufendorf, John Locke, and Christian Wolff. I argue that although Vattel’s doctrine would appear as an ideal type, it was in fact provincially rooted in the narrow context of former dynastic fiefdoms in the Holy Roman Empire. I reach this conclusion through a spatial contextualist method of reading canonical texts in the natural law and law of nations traditions. I find that the shared linguistic practices that emerged to conceptualize and defend territorial states often relied upon assuming preexisting communities who laid claim to the land as their ‘native country.’