Language naming systems are local ways of organising diversity, yet the language names used by linguists are sometimes incommensurable with the lived social reality of speakers. The process of assigning language names is not neutral, trivial or objective: it is a highly political process driven and shaped by understandings of group identity, similarity and difference. Closer attention to local perspectives on language naming offers important insights into ideologies around social and linguistic differentiation. This paper draws together accounts of diverse language naming practices from across Indigenous Australia and applies a close lens to the region of western Arnhem Land. Through an examination of three groups (speakers of Bininj Kunwok, Mawng, and Burarra), we describe the range of strategies speakers use to divide up their local language ecologies, practices for naming lects, and the role of variation in the processes of differentiation. Naming practices between these groups show interesting similarities but also striking differences. We further highlight the interplay between two key processes which characterise local language naming strategies in the region: the 'erasure' of difference, typically from the perspective of a politically more powerful group, and the intentional creation of linguistic differentiation, or ausbau.