The Ryukyuan languages (Japonic) are spoken on the Ryukyu Islands in the southern part of the Japanese archipelago. They are sister languages to Japanese, split off from a common ancestor language more than thousand years ago, and are generally divided into five language groups: Amami, Okinawa, Miyako, Yaeyama and Yonaguni. Once spoken in the independent Ryukyu Kingdom (1406-1879) with its distinct culture, they are now endangered with virtually no transfer to younger generations. All speakers are at least in their 50’s in general and all are bilingual in Japanese. The exact number of speakers is unknown, but can be estimated at around 20,000 at most based on age demographics. The Ryukyuan languages are primarily SOV, agglutinative, mora-timed and have contrastive pitch accent. They retain a fair amount of features found in Old Japanese, but also show distinct aspects not found in Standard Japanese. They are mutually unintelligible with mainland Japanese varieties, but generally also with each other.
Heinrich, P., Miyara, S., & Shimoji, M. (Eds.). (2015). Handbook of the Ryukyuan languages: History, structure, and use (Vol. 11). Walter de Gruyter GmbH & Co KG.