QUAESTIONES MEDII AEVI NOVAE (2011) ANDRZEJ JANECZEK WARSZAWA TOWNS ON THE FRONTIER  THE FRONTIER IN TOWNS. MULTIETHNIC URBAN COMMUNITIES IN RED RUTHENIA IN LATE MIDDLE AGES MULTITUDE OF BOUNDARIES, VARIETY OF FRONTIERS In modern historiography, sociology and anthropology, the notions of boundary and frontier have gained great popularity. They have been freed from an exclusively geographical context and their meaning has been extended far beyond the traditional scope. They are no longer distinguished only by the spatial aspect. They have begun to be used not only to describe and explain phenomena and processes occurring in geopolitical space, but also to define the relations between groups and the bonds connecting or distancing the communities from one another in social space, as well as to indicate divisions, diversification and encounters in the world of culture. Social and cultural boundaries have become autonomous and independent concepts, sometimes even entirely unconnected with the idea of territorial borders. Such a significant extension of meaning, the loss of the original literal sense and at the same time the popularization of the notion of boundaries as attractive buzz words, may give an impression of overusing the concept and raise concerns that they have become  in spite of what they mean themselves  unlimited notions. Meanwhile, a frontier in the meaning that will be used here is a situation, which although not rare, is of special character at the same time. It seems that certain types of behaviour, attitudes and institutions as well as forms of social life can emerge and develop only on a frontier which embraces these three characteristics in particular. Therefore, without giving up the notion of frontier as an inspiring metaphor for a gradational overlap and interpenetration of cultures, as an idea which brings to mind justified associations of neighbourhood and cohabitation of ethnic groups or as a notion referring exclusively to the