Okinohara Site, Archaeological settlement in Akazawa, Tsunan, Japan

The Okinohara Site occupies a river terrace about 160 meters above the Shinano River bed in the Akazawa area of Tsunan. Excavations from 1972 to 1973 uncovered 49 pit dwellings, three large rectangular buildings and one stone-paved structure around a circular plaza 120 meters across. The buildings were made mainly of chestnut wood, and the site is now backfilled as an empty field.

The site was inhabited during the middle Jomon period roughly 5000 to 4000 years ago and was excavated during the 1970s. These discoveries proved important for understanding settlement patterns of that era and led to its designation as a National Historic Site in 1978.

The site gave its name to Okinohara-style pottery: deep bowls with a small base, widening like a bucket and often tilted to one side, with decoration limited to the rim and upper body. Excavations also yielded over 1,686 flame-style vessels, stone tools and lumps of carbonized material called "Jomon cookies".

The location is about 15 minutes by car from Tsunan Station, which connects the area by train. The excavated artifacts and detailed information about the site can be viewed at the Tsunan Town History and Folklore Museum.

Excavations found over 1,686 pieces of flame-style Jomon pottery at the site, alongside the locally made Okinohara-type vessels. Small lumps of carbonized organic material dubbed "Jomon cookies" were also unearthed, thought to be the remains of some form of preserved bread.