Modern international relations theory purports to be universally applicable, but was inspired largely by the interstate politics of the West. From antiquity to the late nineteenth century, the international system of East Asia differed from those of the West on the four variables that international relations theory deems to be most important in shaping interstate politics: the balance of power, the regime types of most states, the role of trade, and the prevailing international norms. We therefore test international relations theory's claim to universality against the history of East Asia "before the West." We assess the extent to which the predictions of international relations theory fit the interstate politics of East Asia, focusing on cooperation under hegemony, the enforcement of order, international norms, trade relations, changes in the balance of power, changes in polarity, and state formation. We find several shortcomings that suggest profitable new avenues for improving international relations theory.