In contemporary politics and research, 'ethnicity' is an almost ubiquitous concept. In this excellent book Heiskanen shows the importance of dissecting the conceptual underpinnings of this seemingly transhistorical concept. Heiskanen shows that 'ethnicity' is a surprisingly recent conceptual innovation. Indeed, until the early 20th century, the 'imperial trinity of nation, race, and tribe’ served as the main point of reference for statesmen and scholars alike. With the dismantling of European empires, and the establishment of a postcolonial system populated by formally equal nation-states, these concepts fell into disfavor. The term 'nation' was avoided due to its association with independent statehood; 'race' was avoided thanks to its association with individual pathologies; and the term 'tribe', was consigned to a colonial past that had ranked societies by their perceived level of development. Amid this monumental transition, 'ethnicity' filled the void left by the three terms. It acted as a filler term allowing politicians to discuss stateless minorities without evoking their right to independent statehood; it became an umbrella term to denote domestic identity groups, regardless of their constituting racial or cultural differences; and it enabled scholars to conceptualize identity groups in a way applicable to all societies. However, the racial and civilizational hierarchies of the colonial era did not vanish into thin air. To give just one example, the term 'ethnicity' is disproportionately often used to refer to non-Western societies, to juxtapose a seemingly 'civic' West from an 'ethnic non-West'. Future research might build on this thought-provoking book by studying in more detail the conceptual diffusion of 'ethnicity' outside Europe and the implications of this conceptual innovation for political claim-making and conflict around the world.