The Satsugū dialect is commonly cited for its mutual unintelligibility to even its neighboring Kyūshū variants,[2][3][4] prompting the Max Planck Institute for Evolutionary Anthropology to classify it as a distinct language in the Japanesic branch in its Glottolog database.

Variations in pronunciation, words, expressions and grammatical constructions may occur between neighboring cities, towns and villages, with peripheral islands exhibiting greater divergence due to isolation.

As such, Satsugū may be considered a dialect continuum, differing only slightly between areas that are geographically close, and gradually decreasing in mutual intelligibility as the distances become greater.

By this token, all major areas of the mainland—including Satsuma, Ōsumi, Morokata, and possibly also a small fraction of southern Kumamoto—may form a single, closely related dialect branch with no precise boundaries due to continuous contact between the regions.

[22] The two were sent across the country to the capital of Saint Petersburg, where they were received in audience by Empress Anna Ivanovna, and later baptized in the Russian Orthodox Church.

[24] These transliterations provide not only the oldest record of the Satsugū dialect, but have also been cited for their comprehensive evidence of the history, phonology and variability of the Japanese language.

When Japan started slowly opening up to the rest of the world in the mid 19th century, Satsuma was one of the first domains to embrace Western culture and methods.

When the Namamugi Incident of September 14, 1862 occurred, political and ideological differences between the United Kingdom and Satsuma Province sparked outrage and quickly boiled into the Anglo-Satsuma War.

[28] The Satsugū dialect, which had a predominant role in samurai affairs and equally the police hierarchy system throughout Japan,[29] steadily declined in influence following this defeat.

Dozens of international phone calls had been made using the Satsugū dialect, and despite being able to eavesdrop on the conversations being sent back and forth, the United States was unable to determine the language spoken.

Examples pulled from a research survey include 気張いやんせ kibai-yanse "please do your best", おやっとさあ oyattosaa "thank you for your work", あにょ anyo "older brother", げんね genne "shy", and がっつい gattsui "exactly", among numerous others.

[37] The same research also revealed through interviews that, while people generally felt a positive vibe to hearing the traditional dialect spoken, those under the age of 40 expressed some difficulty understanding.

In Tanegashima, the mid back vowel /o/ still exhibits rounding in some words such as 魚 io [iʷo] "fish" or 塩 shio [ɕiʷo] "salt".

In terms of the latter, the distinction between all four of the traditional yotsugana (四つ仮名, literally "four kana") syllables ジ /zi/, ヂ /di/, ズ /zu/ and ヅ /du/ is still preserved within the Kyūshū portion of Kagoshima.

For example, the imperative form of "eat", which is 食え /kue/ in standard Japanese, becomes 食ぇ /kʷe/ in the dialect,[49] which contrasts both 崩え /kue/ "landslide" (pronounced [kuʲe̞])[49] and 貝 /ke/ "shellfish".

Before nasal syllables, the moraic obstruent may be realized, depending on the regional dialect, as a glottal stop [ʔ], so that /kiQne/ "fox" is pronounced [kiʔne].

This effectively means that the placement of the high tone in accented or unaccented units will shift rightwards to the penultimate or final syllable of the phrase when other morphemes, auxiliaries or grammatical particles such as が ga are appended at the end.

For example, 寺 tera "temple" and 酒 sake are normally accented, but when the honorific prefix お o- is added, they shift to an unaccented pattern: お寺 otera and お酒 osake.

[63] The standard Japanese plain copula だ da is replaced by the Satsugū dialectal variation じゃ ja, which has further developed into や ya in some parts of the Satsuma Peninsula, most notably the capital city, Kagoshima.

[68] For example, the adjectives "cold" and "exhausted" may surface as sanka and tesoka, or sami and tesoi (variants: sabi and tese) depending on the speaker and region.

Like standard Japanese particles, they act as suffixes, prepositions or words immediately following the noun, verb, adjective or phrase that they modify, and are used to indicate the relationship between the various elements of a sentence.

In mainland Kagoshima, the two suffixes どん -don and たっ -taʔ are commonly appended to the pronouns above in order to indicate plurality: おい oi "I" → おいどん oidon "we", おはん ohan "you" → おはんたっ ohantaʔ "you (pl)".

[82] Due to its pervasive use in the Satsuma region, the ending domo may have come to be associated with the speech of samurais, and thus carries a slight condescending or humble connotation in standard Japanese.

It is worth noting, however, that the honorific suffix stems from the historical form 殿 dono, now used in standard Japanese almost uniquely in business correspondences.

For instance, -don can be used in a very pompous manner with the first-person pronoun, resulting in おいどん oidon "I/my esteemed self", which is equivalent to standard Japanese 俺様 oresama.

[44] As with Standard Japanese, demonstratives also occur in the ko- (proximal), so- (mesial), and a- (distal) series, with the corresponding interrogative form as do-.

[89] And lastly, the Satsugū dialect also makes use of an extra series that describes limits using the -shiko suffix, which is roughly the equivalent of the standard Japanese construction -re + -dake or -hodo.

For example, the standard form 書く kaku "write" becomes 書っ kaʔ in the dialects of the mainland as a result of high vowel deletion.

For example, the polite auxiliary verbs もす mosu (or もうす mōsu in Tanegashima) and もんす monsu, sometimes written as 申す and 申んす respectively,[92] are used instead of the standard ending ます -masu.

As a result, multiple variants of the same verb may exist: やる yaru, やす yasu and やんす yansu[68][92] are all formal auxiliaries used in imperative constructions, as in 食もいやんせ tamoi-yanse "please eat".