Japonic languages

Japonic or Japanese–Ryukyuan is a language family comprising Japanese, spoken in the main islands of Japan, and the Ryukyuan languages, spoken in the Ryukyu Islands. The family is universally accepted by linguists, and significant progress has been made in reconstructing the proto-language, Proto-Japonic. The reconstruction implies a split between all dialects of Japanese and all Ryukyuan varieties, probably before the 7th century. The Hachijō language, spoken on the Izu Islands, is also included, but its position within the family is unclear.
Most scholars believe that Japonic was brought to the Japanese archipelago from the Korean peninsula with the Yayoi culture during the 1st millennium BC. There is some fragmentary evidence suggesting that Japonic languages may still have been spoken in central and southern parts of the Korean peninsula in the early centuries AD.
Possible genetic relationships with many other language families have been proposed, most systematically with Koreanic, but no genetic relationship has been conclusively demonstrated.

Classification

The extant Japonic languages belong to two well-defined branches: Japanese and Ryukyuan.
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.
The former wider distribution of Ainu languages is confirmed by placenames in northern Honshu ending in and .
Somewhat later, Japonic languages also spread southward to the Ryukyu Islands. There is fragmentary placename evidence that now-extinct Japonic languages were still spoken in central and southern parts of the Korean peninsula several centuries later.

Japanese

Japanese is the de facto national language of Japan, where it is spoken by about 126 million people. The oldest attestation is Old Japanese, which was recorded using Chinese characters in the 7th and 8th centuries.
It differed from Modern Japanese in having a simple V syllable structure and avoiding vowel sequences. The script also distinguished eight vowels, with two each corresponding to modern i, e and o. Most of the texts reflect the speech of the area around Nara, the eighth-century Japanese capital, but over 300 poems were written in eastern dialects of Old Japanese.
The language experienced a massive influx of Sino-Japanese vocabulary after the introduction of Buddhism in the 6th century and peaking with the wholesale importation of Chinese culture in the 8th and the 9th centuries. The loanwords now account for about half the lexicon. They also affected the sound system of the language by adding compound vowels, syllable-final nasals, and geminate consonants, which became separate morae.
Most of the changes in morphology and syntax reflected in the modern language took place during the Late Middle Japanese period.
Modern mainland Japanese dialects, spoken on Honshu, Kyushu, Shikoku, and Hokkaido, are generally grouped as follows:

Eastern Japanese, including most dialects from Nagoya east, including the modern standard Tokyo dialect.
Western Japanese, including most dialects west of Nagoya, including the Kyoto dialect.
Kyushu dialects, spoken on the island of Kyushu, including the Kagoshima dialect/Satsugū dialect, spoken in Kagoshima Prefecture in southern Kyushu.

The early capitals of Nara and Kyoto lay within the western area, and their Kansai dialect retained its prestige and influence long after the capital was moved to Edo in 1603. Indeed, the Tokyo dialect has several western features not found in other eastern dialects.
Post-war geolinguistic studies have identified bundles of isoglosses, often coinciding with geographic features.

A large bundle, running north–south through the Japanese Alps, forms the basis of the traditional East–West dialect division.
Another set of isoglosses separates peripheral areas, mainly northern Honshu and western Kyushu but also Izumo and the southern part of the Kii Peninsula, from the central area. Numerous innovations have spread through the central area, with the peripheral areas preserving older forms. Researchers have found it more difficult to explain other isoglosses in which peripheral areas share mergers of pitch accent classes and reduction of vowel sequences that are preserved in the central area, particularly the Kansai region.
Several isoglosses run roughly east–west, from Fukushima to the western end of Honshu, and corresponding to the 0 °C isotherm and 1000 mm isohyet.

The Hachijō language, spoken on Hachijō-jima and the Daitō Islands, including Aogashima, is highly divergent and varied. It has a mix of conservative features inherited from Eastern Old Japanese and influences from modern Japanese, making it difficult to classify. Hachijō is an endangered language, with a small population of elderly speakers.

Ryukyuan

The Ryukyuan languages were originally and traditionally spoken throughout the Ryukyu Islands, an island arc stretching between the southern Japanese island of Kyushu and the island of Taiwan. Most of them are considered "definitely" or "critically endangered" because of the spread of mainland Japanese.
Since Old Japanese displayed several innovations that are not shared with Ryukyuan, the two branches must have separated before the 7th century. The move from Kyushu to the Ryukyus may have occurred later and possibly coincided with the rapid expansion of the agricultural Gusuku culture in the 10th and 11th centuries. Such a date would explain the presence in Proto-Ryukyuan of Sino-Japanese vocabulary borrowed from Early Middle Japanese. After the migration to the Ryukyus, there was limited influence from mainland Japan until the conquest of the Ryukyu Kingdom by the Satsuma Domain in 1609.
Ryukyuan varieties are considered dialects of Japanese in Japan but have little intelligibility with Japanese or even among one another. They are divided into northern and southern groups, corresponding to the physical division of the chain by the 250 km-wide Miyako Strait.
Northern Ryukyuan languages are spoken in the northern part of the chain, including the major Amami and Okinawa Islands. They form a single dialect continuum, with mutual unintelligibility between widely separated varieties. The major varieties are, from northeast to southwest:

Kikai, on the island of Kikaijima.
Northern Amami Ōshima, spoken in most of Amami Ōshima
Southern Amami Ōshima, spoken in Setouchi on the southern end of Amami Ōshima.
Tokunoshima, on the island of Tokunoshima.
Okinoerabu, on the island of Okinoerabujima
Yoron, on the island of Yoronjima.
Kunigami or Northern Okinawan, spoken in the northern part of Okinawa Island, including the cities of Nakijin and Nago.
Okinawan, spoken in the central and southern parts of Okinawa Island, and neighboring islands. The prestige dialect is spoken in Naha, and the former city of Shuri. The Shuri dialect was the lingua franca of the Ryukyuan Kingdom, and was first recorded in the 16th century, particularly in the Omoro Sōshi anthology.

There is no agreement on the subgrouping of the varieties. One proposal, adopted by the UNESCO Atlas of the World's Languages in Danger, has three subgroups, with the central "Kunigami" branch comprising varieties from Southern Amami to Northern Okinawan, based on similar vowel systems and patterns of lenition of stops. Pellard suggests a binary division based on shared innovations, with an Amami group including the varieties from Kikai to Yoron, and an Okinawa group comprising the varieties of Okinawa and smaller islands to its west.
Southern Ryukyuan languages are spoken in the southern part of the chain, the Sakishima Islands. They comprise three distinct dialect continua:

Miyako is spoken in the Miyako Islands, with dialects on Irabu and Tarama.
Yaeyama is spoken in the Yaeyama Islands, with dialects on each island, but primarily Ishigaki Island, Iriomote Island, and Taketomi Island.
Yonaguni, spoken on Yonaguni Island, is phonologically distinct but lexically closer to other Yaeyama varieties.

The southern Ryukyus were settled by Japonic-speakers from the northern Ryukyus in the 13th century, leaving no linguistic trace of the indigenous inhabitants of the islands.

Alternative classifications

An alternative classification, based mainly on the development of the pitch accent, groups the highly divergent Kagoshima dialects of southwestern Kyushu with Ryukyuan in a Southwestern branch.
Kyushu and Ryukyuan varieties also share some lexical items, some of which appear to be innovations.
The internal classification by Elisabeth de Boer includes Ryukyuan as a deep subbranch of a Kyūshū–Ryūkyū branch:

Japonic
*Eastern
*Central
*Izumo–Tōhoku
*Kyūshū–Ryūkyū

She also proposes a branch consisting of the Izumo dialect and the Tōhoku dialects, which show similar developments in the pitch accent that she attributes to sea-borne contacts.

Peninsular Japonic

There is fragmentary evidence suggesting that now-extinct Japonic languages were spoken in the central and southern parts of the Korean peninsula. Vovin calls these languages Peninsular Japonic and groups Japanese and Ryukyuan as Insular Japonic.
The most-cited evidence comes from chapter 37 of the , which contains a list of pronunciations and meanings of placenames in the former kingdom of Goguryeo. As the pronunciations are given using Chinese characters, they are difficult to interpret, but several of those from central Korea, in the area south of the Han River captured from Baekje in the 5th century, seem to correspond to Japonic words. Scholars differ on whether they represent the language of Goguryeo or the people that it conquered.
Traces from the south of the peninsula are very sparse:

The Silla placenames listed in Chapter 34 of the are not glossed, but many of them can be explained as Japonic words.
Alexander Vovin proposes Japonic etymologies for two of four Baekje words given in the Book of Liang.
A single word is explicitly attributed to the language of the southern Gaya confederacy, in Chapter 44 of the. It is a word for 'gate' and appears to have a similar form to the Old Japanese word, with the same meaning.
Vovin suggests that the ancient name for the kingdom of Tamna on Jeju Island, tammura, may have a Japonic etymology tani mura 'valley settlement' or tami mura 'people's settlement'. He also proposes Japonic etymologies for two other local words.