Sumatran.

The island of Sumatra and the Barrier Islands lying off its west coast are home to a diverse array of Austronesian languages. For at least a century and a half, a close genetic relationship between many of the non-Malayo-Chamic languages of the region—namely the Batak languages, Simeulue, Nias, Mentawai, and Enggano—has been proposed. Evidence in support of such a group was first thoroughly detailed by Nothofer, who outlined sound correspondences and phonological innovations for a Barrier Island–Batak subgroup. Building upon Nothofer's proposal and recent observations about the languages of Sumatra, this paper proposes a far-reaching language group we call Sumatran, comprising Nothofer's Barrier Island–Batak group as well as Gayo, spoken in northern Sumatra, and Nasal, spoken in southwestern Sumatra. We also provide stronger evidence for the inclusion of Enggano, spoken on the southernmost Barrier Island, which Nothofer only tentatively included. To support this proposal, we outline shared innovations that establish the foundation of what constitutes the Sumatran language subgroup. [ABSTRACT FROM AUTHOR]