Although there is a clear rise in academic interest in region formation, theoretical approaches to the topic vary greatly, stemming from geopolitical identifications of objective regional boundaries, through functionalist ideas of regional linkages, to post-structuralist ideas about fluid regional belonging. This article provides a typology of region formation approaches, based on the ontological assumptions of its authors. The typology is based on two main debates within contemporary international relations ontology: regarding the basic components of reality (material vs. ideational) and regarding the status of theories (transfactual vs. phenomenalist). The presented matrix provides an ideal-typical position for each of these four iterations and illustrates its viability in the case of region formation literature on the Asia-Pacific. Doing so, the text contributes to (meta) theoretical discussions of how regions are formed while at the same time illustrating the often-overlooked stories of region formation.
