Proto-Tsushiman

Proto-Tsushiman was an Austronesian language spoken in the island of Tsushima during the Taoguan Period of Tsushiman history. It is the direct ancestor of the Tsushiman language. Once believed to be a direct descendant of Proto-Austronesian, it is now considered to have been a dialect of Proto-Donghainese, the others being the Nansei language and Zhejiang language. While no direct record of Proto-Tsushiman exists, comparison of attested Classical Tsushiman words with no Old Chinese equivalent with modern Austronesian languages make clear its existence.

Grammar
Proto-Tsushiman is a VOS language, as was its predecessor and its modern form. It uses infixes extensively, similar to modern Formosan and Philippine languages but very much unlike modern Tsushiman.

ma- prefix: marks stative, as well as adjectives ka- prefix: marks inchoative stative

Vocabulary
Proto-Tsushiman's vocabulary primarily consists of terms derived directly from Proto-Austronesian through Proto-Donghainese, and terms coined by compounding these roots. Scholars have noted that one Proto-Austronesian word may sometimes have two or more reflexes in Proto-Tsushiman with slightly different meanings; it is debated whether these are variations created to distinguish their meanings, or if they were borrowed from another Donghainese language such as the Nansei language. There are also a few loanwords from Proto-Japonic.