An increasing number of international law scholars have become drawn in recent years to the study of political economy. In trying to situate the linkage between international law and political economy in its purported historical context, much of this scholarship has tended to construct a vision of a historical relationship between them that typically extends no further back than the 19th century. In contrast, this article situates this relationship in a longue duree with two aims. First, to outline some of the extra-legal factors that installed the historical conditions for a style of international law to emerge that would facilitate ‘public’ administrative capacity and the institutional practices that underwrite forms and processes of contemporary ‘private’ economic life. And second, to experiment with ways that the concept of political economy may be used within international law scholarship.