Proto-Japonic language

[3] Most scholars believe that Japonic was brought to northern Kyushu from the Korean peninsula around 700 to 300 BC by wet-rice farmers of the Yayoi culture and spread throughout the Japanese archipelago, replacing indigenous languages.

[7] They are divided into northern and southern groups, corresponding to the physical division of the chain by the 250 km-wide Miyako Strait.

[10] The migration to the Ryukyus from southern Kyushu may have coincided with the rapid expansion of the agricultural Gusuku culture in the 10th and 11th centuries.

[11] After this migration, there was limited influence from mainland Japan until the conquest of the Ryukyu Kingdom by the Satsuma Domain in 1609.

The complementary approach of comparative reconstruction from the dialects and Ryukyuan has grown in importance since the work of Shirō Hattori in the 1970s.

[14] The other Old Japanese consonants are projected back to Proto-Japonic except that authors disagree on whether the sources of Old Japanese w and y should be reconstructed as glides *w and *j or as voiced stops *b and *d respectively, based on Ryukyuan reflexes:[15] Some authors, including advocates of a genetic relationship with Korean and other northeast-Asian languages, argue that Southern Ryukyuan initial /b/ and Yonaguni /d/ are retentions of Proto-Japonic voiced stops *b and *d that became /w/ and /j/ elsewhere through a process of lenition.

[18] However, many linguists, especially in Japan, prefer the opposite hypothesis, namely that Southern Ryukyuan initial /b/ and Yonaguni /d/ are derived from local innovations in which Proto-Japonic *w and *j underwent fortition.

Some authors propose a high central vowel *ɨ to account for these alternations, but there is no evidence for it in Ryukyuan or Eastern Old Japanese.

[38] In each of the modern varieties, the pattern of high and low pitches is shown across both syllables and a following neutral particle.