International Relations scholars have drawn on history ever since the field first formed in the early twentieth century. They have trawled the beds of the past, far and near, to probe, substantiate, and analogize in the pursuit of theories about what have been taken to be the main pillars of contemporary international life: states and the institutions and systems that form around their interaction. Even if states as we now know them did not exist in a given period, one could still mine insights from the interaction of any relatively autonomous political units, from city-states to tribal bands.See, e.g., Marcus Fischer, ‘Feudal Europe, 800–1300: Communal Discourse and Conflictual Practices’, International Organization, 46 (1992), pp. 427–66; and Adam Watson, The Evolution of International Society (London, 1992).