The southern variety of the Setouchi township may be a distinct language more closely related to Okinawan than it is to northern Ōshima.

The subdivisions of Amami–Okinawan, however, remain a matter of scholarly debate, with two major hypotheses: The two-subdivision hypothesis is convenient for discussing the modern languages since the posited linguistic boundary corresponds to the centuries-old administrative boundary that today separates Kagoshima and Okinawa Prefectures.

[4] The distribution of Southern Amami Ōshima roughly corresponds to Setouchi Town, including offshore islands.

[4] Shibata et al. (1984) takes a lexicostatistic approach to subgrouping Northern Amami Ōshima dialects:[5] In addition, Sani, a small community on a peninsula at the northern tip of the island, is known to have distinct phonology.

Based on phonetic and lexical evidence, Shibata et al. (1984) subdivide Southern Amami Ōshima into reflecting the administrative divisions during the Edo period.

[6] According to Osada Suma (1902–1998), the dialect of Yamatohama, Yamato Village of Amami Ōshima had yumuta /ˈjumuθa/ for 'language', shimayumuta /simaˈjumuθa/ for 'island language' (i.e. Amami Ōshima) and Yamatoguchi /ˈjamaθoɡuci/[clarification needed] for the language of mainland Japan (i.e. Standard Japanese).

1923), a local historian from Amami Ōshima, shimaguchi contrasted with Yamatoguchi, while shimayumuta was associated with accentual and intonational differences among various shima (villages).

[8] Ebara Yoshimori (1905–1988), a folklorist from Naze, Amami Ōshima, conjectured that shimaguchi was of relatively recent origin, possibly made through analogy with Yamatoguchi.

[10] In the southern Shodon dialect, the consonants /p t tɕ k ɕ ɾ m n/ occur at the end of a word or syllable, as in /k˭upʰ/ 'neck', /sakʰɾa/ 'cherry blossom' and /t˭ɨɾɡjo/ 'well'.