Social scientists are so much focused on the concept of boundaries, that there is no question it exists. It's long time it's proved people always have some concept of 'us' and of 'them' in their mind, it means socially they make distinctions. And so social scientists are interested in social phenomenas emerging due to such differentiation. There is a whole study of boundaries done. But the boundary concept is not full - it's just social boundary concept, concept mostly defined by self identification which might define or identify ethnos, but not whole ethnical culture and NEITHER archaeological culture. Archeologists define archeological cultures, which may be ethincal cultures, cultures identifying themselves as one, but it is never a rule. All if far from geographical boundaries as well as the culture and it's spread is understood differentially. Geographers try to unite all possible aspects, drawing and presenting the boundaries of cultural regions.
Let's look at some archaeological boundary of Lithuanian archaeological culture drawn.
