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How and when was Japan settled by speakers of Japanese? Exploring the clues to Japanese prehistory preserved in old dialect divisions

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Regional tone accents reveal history of Japan’s migrations

By analysing the tone systems of Japanese dialects, the JapPrehistMigration project shed light on migration patterns across Early Japan.


The Japanese language is thought to have been introduced to Japan from the Korean peninsula alongside wet rice agriculture around 900 BCE. Despite the indigenous populations likely speaking many languages, Japan now has only two: Japanese and Ainu. This indicates the replacement of hunter–gatherer societies with agricultural societies, a hypothesis supported by the fact that remnants of Ainu remain in the northeast – the last areas reached by the new rice farmers. By analysing Japanese tone systems, the EU-supported project JapPrehistMigration has added more detail to Japan’s migration story.

Reconstructing proto-Japanese

The proto-Japanese tone system refers to the earliest tone system that can be reconstructed, based on a comparison of modern tone systems with tone marks found in manuscripts from the Middle Japanese period (11th-14th century). In the 1930s, the tone marks found in the old manuscripts – mostly from the former capital of Kyoto – were deliberately given tonal values to align them with modern Kyoto’s tonal system. “This made sense at the time as they didn’t know that Kyoto’s tonal type is restricted to central Japan, surrounded by the older Tokyo type, and was actually an innovation. But these efforts have hampered the correct reconstruction of Japanese tonal developments,” notes project coordinator Elisabeth de Boer from the Ruhr University Bochum, the project host. “This idea was first proposed in 1979 by S. R. Ramsey, but nobody investigated it until me.” Despite being geographically separated, the Gairin (‘outer circle’) modern tone systems share identical innovations. The tone rules for noun compounds in these areas also seemed different from those of other dialects, suggesting the Gairin type formed a separate lineage that developed once, then spread through migration. Conducting extensive fieldwork in Gairin areas, tones were analysed, entered into a database and cross-referenced with modern dialects and Middle Japanese.

Explaining the ‘compound puzzle’

The team found that the rules for compounds in modern dialects were fundamentally different than previously thought. What had been regarded as irregularities were traced back to distinctions in proto-Japanese. “The compound rules in all dialects preserved archaic distinctions in a fossilised form, and confirmed my reconstruction of the proto-Japanese tones,” adds De Boer. These insights, which no longer viewed the Gairin tone systems as isolated, explain three geographically separate dialect areas along the Sea of Japan coast which have intrigued researchers. These can now be seen to represent different stages in a single dialect, with each separating through migration. A wave of migration in the 1st century CE brought a dialect with a distinct phonology and an archaic tone system from Izumo – once one of the most powerful kingdoms in Japan – to the Noto peninsula. After extensive innovations resulted in a Gairin-type tone system, a second migration in the 6th century CE from Izumo introduced the culture of the rice farmers to northeast Honshu, explaining the close resemblance in both phonology and tone between these areas. Resemblances in DNA, folk music and the shape of burial tombs offer supporting evidence for these migrations. After COVID-19 halted fieldwork, the team concentrated on inputting published tone data from across Japan into their database. “Japanese colleagues are interested in adding data, so I hope to make this database open access, which, complemented by computational analysis, should lead to future insights,” says De Boer.


JapPrehistMigration, language, Japanese, agriculture, hunter–gatherer, Gairin, tone, dialect, migration, Ainu, manuscripts

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