This is a highly contextualized essay on the history of etnos theory from roughly the 18th century to the 21st century. The introduction demonstrates how various concepts of identity arose from the concrete experiences that specific ethnographers had with the people who hosted them, and that these sometimes-competing accounts of etnos, minzu, and ethnie were underwritten by concrete experiences. Historically, the introduction would touch on the first usage of the etno- prefix by Baltic Germans studying Russian hinterlands, continue through the development of the notion in German and French theory. Here the development is linked both to an evolving consciousness of the distinctiveness of human form (i.e. Racial anthropology) and the gradual process by which ethnography/social anthropology carved out a space for itself independent of what is today biological anthropology. The introduction then poses the question of how to speak about the life histories of these concepts as embodied in the lives of several concrete individuals, and as debated in several regional theatres from one side of Eurasia to another. Moving across the case studies, which are the heart of the volume, the introduction will follow the threads of argument as they lead up until the present day. In terms of regional theatres, we will focus on ‘Southern Russia/Ukraine’, ‘Northern Russia/Pomoria’ and ‘Siberia/Northern China’. The introduction will then lead the reader to the present day from the ‘revival’ of etnos theory by Julian Bromley and the way that nationality and identity is debated in contemporary China.