The article actualizes the significance of interdisciplinary research into a region on the basis of a case study of East Prussia and seeks to bring out a problematic character of “professional regional history” in the context of the contemporary science of history. One of the major aims of the article is to emphasize theoretical reflections on interdisciplinary research into a region by featuring some research methods, viz. micro-history and applied history. The employment of the said methods that encourages multiple and precise studies of historical personalities and details typical of the collective consciousness of individuals in a local territory opens an opportunity to also grasp the relationships between cultural, social, economic, and political factors by revealing a clear view of the historical context.