This contribution focuses on the multifaceted process of Indo-Europeanization which started out, in the Pontic-Caspian region, with the formation of a distinct ethno-cultural epicenter, the Proto-Indo-European complex. Since the late Neolithic, the Indo-Europeanization of Europe and parts of Asia produced various scenarios of contact and conflict. Altogether seven dimensions are highlighted as essential for the study of the contacts which unfolded between Indo-Europeans and non-Indo-European populations (i.e. Uralians, Caucasians, ancient populations in southern and central Europe). Selective aspects of cultural and linguistic fusion processes during the Neolithic and subsequent periods are discussed, and the controversial term ‘migration’ is redefined.