it only occurs in compounds, and it is only present in three dialects of the Southern Ryukyuan language group. Also, the doublet wo meaning 'hemp' is attested in Western Old Japanese and Southern Ryukyuan languages. It is thus plausible to assume a borrowed term.

Hudson & Robbeets (2020) suggested that there are traces of a pre-Nivkh substratum in Korean. According to the hypothesis, ancestral