Given recent developments in world politics—notably, Russia's war on Ukraine—studying empires is in vogue again in international relations (IR). It has to be said, however, that our field has always had a complicated relationship with the concept of empire. On the one hand, we have often defined the international as a break from the imperial era. On the other hand, arguments about the continued presence of hierarchy within the international system and/or the possibility of its revival makes research on empires more attractive to IR scholars at various intervals. A good example of this is the American empire debate.

However, much of the IR literature on empire suffers from a lack of imagination as to which empires to study. If we are not talking about European empires of the nineteenth century, then we must be talking about Rome. As a result, many seemingly universal definitions of empire are laden with assumptions that are not historically generalizable. For example, they tend to assume empires are always created by bounded core-states (city or nation), and that the distinctions between foreign/domestic are transhistorical. Thankfully, a recent spate of research in historical IR has challenged some of these received wisdoms by drawing our attention beyond Europe, especially to Asia. Here, Andrew Phillips' How the East Was Won or Hendrik Spru