Artifacts Excavated from the Ushiroya Site in Saitama

Artifacts from the Ushiroya Site: A Window into Jomon Life in Saitama

Nestled in the city of Okegawa in Saitama Prefecture, the Ushiroya Site (後谷遺跡) has yielded one of the most remarkable collections of Jomon-period artifacts in the Kanto region. Designated as an Important Cultural Property of Japan in 2011, this assemblage of 645 items — spanning pottery, clay figurines, wooden tools, lacquerware, and stone implements — offers an extraordinarily vivid portrait of life during the Late to Final Jomon period, roughly 3,500 to 2,500 years ago. What makes this collection exceptional is not just its diversity, but the rare state of preservation achieved thanks to the site's waterlogged lowland environment, which protected organic materials that would normally have decomposed over millennia.

The Ushiroya Site: Geography and Excavation History

The Ushiroya Site is located in the Akahori district of Okegawa City, on the northern part of the Omiya Plateau. The site extends from a tongue-shaped terrace on the eastern edge of the plateau down into the surrounding lowland along the Moto-Arakawa River. This combination of elevated and low-lying terrain provided ideal conditions for both habitation and the preservation of archaeological materials.

Archaeological investigations at the site began in 1966 with an excavation by the Urawa Archaeological Society. Over subsequent decades, five major excavation campaigns were carried out. The fourth excavation, conducted between 1987 and 1989 in connection with the construction of an industrial park, proved to be the most productive. Researchers uncovered the remains of 14 pit dwellings, 26 storage pits, 45 hearths, and several remarkable wooden structures in the lowland area, including four timber frameworks and a wooden walkway — features that suggest an organized settlement with both residential and communal spaces.

Why These Artifacts Are Designated as an Important Cultural Property

The 645 items designated as Important Cultural Property comprise 324 pottery and clay objects, 52 wooden tools and implements, 13 lacquerware items, and 256 stone tools and stone products. Together, they form a comprehensive record of Late to Final Jomon culture in the Kanto region, offering insights into the daily activities, craft technologies, trade networks, and spiritual practices of the people who lived here thousands of years ago.

Several factors make this collection stand out among Jomon archaeological sites in Japan. First, the waterlogged conditions of the lowland preserved wooden and lacquer objects that rarely survive at other sites. Second, the sheer variety of artifact types — from utilitarian tools to elaborate personal ornaments — paints a complete picture of Jomon society. Third, many objects retain their original coloring and surface treatments, including red pigment and lacquer finishes, providing rare evidence of Jomon decorative arts. The collection is recognized as an extremely important body of material for understanding the lifeways, technologies, and spiritual activities of the Late to Final Jomon period in the Kanto region.

Highlights of the Collection

Visiting the Collection

The designated artifacts are housed at the Okegawa City Museum of History and Folklore (桶川市歴史民俗資料館), located within the Kawataya Lifelong Learning Center. The museum presents a selection of the Ushiroya Site artifacts in a well-organized exhibition that covers Okegawa's history from prehistoric times through the Edo period. Visitors can see the owl-shaped dogu figurines, red lacquered combs, ear ornaments, and other highlights up close. The museum underwent a renovation and presents engaging displays including digital exhibits and a large-screen presentation of local folk traditions.

Admission is free, making this an excellent destination for anyone interested in Japanese prehistory. While English signage is limited, the artifacts themselves are displayed clearly and the visual impact of the collection transcends language barriers. A nine-year conservation project completed in 2021 ensured that 598 of the 645 designated items have been carefully restored, with custom-made paulownia wood storage boxes crafted for each artifact.

Surrounding Attractions

Okegawa City offers several other points of interest that complement a visit to the Ushiroya Site collection. Shiroyama Park, located nearby, preserves the remains of Mitsugi Castle from the Sengoku (Warring States) period and offers pleasant walking trails through wooded terrain. The Kumano Shrine Kofun (ancient burial mound), also in the Kawataya district, is a circular tomb from the Kofun period that yielded its own significant archaeological finds.

History enthusiasts will also enjoy exploring the remnants of the Okegawa-juku post station along the old Nakasendo highway. The Takemura Ryokan, built in 1852, is a surviving inn from the post-station era, and the Kobayashi Family Residence preserves the architecture of a former travelers' lodge. Okegawa was historically famous for safflower (benibana) production, and the city still celebrates this heritage with events and exhibitions.

For those wishing to explore more Jomon-period archaeology in the region, the Saitama Prefectural Museum of History and Folklore in nearby Omiya offers broader context on the prehistoric cultures of the Kanto Plain. The Tokyo National Museum in Ueno also periodically exhibits Jomon artifacts, including items on loan from the Ushiroya collection — some pieces were even displayed in Paris at the Maison de la Culture du Japon in 2018.