From the moment that Prussia entered the world of the crusade movement and the zone of Western European external expansion in the thirteenth century, and was quickly dominated by the Teutonic Order, the new Prussian land created by the Order became a transitional area and a frontier country. A significant aspect of Prussia's character was ethnic diversity and a consequent multiculturalism. This collective volume takes up the subject of ethnicity in Prussia between the 13th and 16th centuries and shows several other aspects of this phenomenon in a region on the outskirts of late medieval Europe. Lithuanians arriving from the east, Poles migrating from the south and Curonians living in the north-eastern peripheries come to light, but the volumes also analyse issues of interethnic relations, both in the so-called 'period of conquest' (13th century) and at the turn of the Middle Ages and the Early Modern period (15th/16th centuries). Also, the issue of linguistic differentiation among the predominantly German-speaking brothers of the Teutonic Order, previously unnoticed in historiography, although difficult to grasp, is presented. These eight papers offer a new contribution to the subject of multiethnicity in late medieval Prussia, still not fully researched and understood. As such, it should provide an interesting historical analysis for English-speaking medievalists and those interested in the history of the southern regions of the Baltic Sea.