Rukai

Rukai (Drekay), spoken by ~10K people across the Pingtung, Kaohsiung and Taitung mountains of southern Taiwan, is one of the most divergent Austronesian languages — Glottolog and most Formosanists place it on its own primary branch, coordinate with the rest of the family (i.e. as old a split as Proto-Austronesian itself). It has six recognised dialects (Tanan, Labuan, Budai, Maga, Tona, Mantauran), some so distinct (notably Mantauran) that they are scarcely mutually intelligible. Phonologically it preserves a four-vowel system /i e a u/ (some dialects add /ɨ/) and a uvular /q/, and grammatically uses Austronesian-style focus marking but lacks the full four-way voice system seen in most other Formosan languages, a typological puzzle central to debates on Proto-Austronesian reconstruction.