Karatsu Matsuura Tombs (Hayamajiri Dolmen Group / Otomo Site

Karatsu Matsuura Tomb Group: Ancient Gateways Between Japan and the Korean Peninsula

On the Karatsu Plain of northwestern Saga Prefecture, facing the Genkai-nada Sea, lies a remarkable collection of burial sites that together tell the story of how continental culture first took root in the Japanese archipelago. Collectively known as the Karatsu Matsuura Tomb Group (唐津松浦墳墓群), these four nationally designated historic sites — Hayamajiri Dolmen Group, Otomo Site, Morita Dolmen Group, and Sakuranobaba Site — span the entire Yayoi period, from its earliest inception through to the Late Yayoi era. They offer a vivid, tangible record of changing burial customs, cross-sea exchange, and the rise of powerful chieftains in what ancient Chinese chronicles called the Kingdom of Matsuro (末盧国).

The Karatsu Plain: Crossroads of East Asian Civilization

The Karatsu Plain sits at the northwestern edge of Saga Prefecture, where the Matsuura River meets Karatsu Bay. From here, the sea route to the Korean Peninsula is strikingly short — sailing north leads to Iki Island, then Tsushima, and onward to the southern tip of the peninsula. This geographic proximity made the Karatsu area one of the first places in Japan to receive new cultural influences from the Asian continent, including wet-rice agriculture, bronze implements, and novel burial practices.

The Chinese historical text "Records of the Three Kingdoms" (魏志倭人伝, Wei Zhi Wa Jin Zhuan), compiled in the 3rd century CE, describes the Kingdom of Matsuro as a coastal community where around four thousand households lived along mountains and the sea, and the people excelled at fishing and diving for abalone. Modern scholars widely identify this kingdom with the Karatsu area, and the archaeological evidence from the Karatsu Matsuura Tomb Group powerfully supports this identification.

Hayamajiri Dolmen Group (葉山尻支石墓群)

The Hayamajiri Dolmen Group is located on a hillside at approximately 20 meters elevation, extending from the slopes of Mount Iimori in the eastern part of the Karatsu Plain. Originally designated as a national historic site in 1966, it represents one of the earliest and most important dolmen burial sites in Japan.

Discovered in 1951 during land development, the site was excavated in 1952 and 1953. Archaeologists uncovered five dolmens (shisekibo) and twenty-six jar burials (kamekanbo). The dolmens date to the Early to Middle Yayoi period. Each capstone is made of granite, with a rounded rectangular or oval shape measuring 1.3 to 2.0 meters in length, 1.15 to 1.4 meters in width, and 0.2 to 0.5 meters in thickness, supported by four to six upright support stones.

Notably, jasper tubular beads (hekigyokusei kudatama) were found in some of the jar burials, indicating a degree of social status and access to precious materials. The site was originally designated for its importance in understanding cultural exchange with the Asian continent. In 2014, when the three additional sites were added, the monument was renamed to its current comprehensive title.

Otomo Site (大友遺跡)

The Otomo Site sits at the northern tip of the Higashimatsuura Peninsula, directly facing the Genkai-nada Sea on the coastline. This location, closer to the open ocean than the other sites in the group, provides crucial evidence for the very earliest adoption of dolmen burials in northern Kyushu.

The dolmens at Otomo date to the Earliest Yayoi period — specifically the Yusu-shiki pottery phase, which marks the transition from the Late Jomon to the earliest Yayoi culture. The substructure of these dolmens features stones arranged along the walls of a burial pit, creating what archaeologists call a "stone-enclosed pit" (ishigakoi no dokou). This construction technique closely resembles dolmen styles found on the Korean Peninsula, making the Otomo dolmens among the most Korean-like burial structures in all of northern Kyushu.

These earliest dolmens were later surrounded by jar burials, showing how the community evolved its burial practices over time while maintaining connections to both continental traditions and emerging local customs.

Morita Dolmen Group (森田支石墓群)

The Morita Dolmen Group adds further depth to our understanding of Yayoi-period burial diversity on the Karatsu Plain. Like Hayamajiri, this site features dolmen burials from the Early Yayoi period, providing comparative data on how this continental burial practice was adopted and adapted across the region.

Together with Hayamajiri and Otomo, the Morita site demonstrates that dolmen construction was not an isolated phenomenon but a widespread practice across the Karatsu area during the Early Yayoi period. A distinctive feature shared among these sites is the characteristic practice of inverting jar coffins — both single and double jars were placed upside down, a burial method unique to this region.

Sakuranobaba Site (桜馬場遺跡): The Royal Tomb of Matsuro

The Sakuranobaba Site holds a special place in Japanese archaeology as the presumed royal burial ground of the Kingdom of Matsuro. Located on a low sand dune along the southwestern edge of Karatsu Bay, at an elevation of approximately six meters, this site dates primarily to the Late Yayoi period and represents the culmination of burial culture in the Karatsu area.

The site was first discovered in 1944 during World War II, when workers digging an air-raid shelter accidentally unearthed a jar burial containing an extraordinarily rich collection of grave goods. These included two Chinese bronze mirrors of the "houkaku-kiku" type (方格規矩鏡), twenty-six hooked bronze bracelets, three tomoe-shaped bronze ornaments, iron sword fragments, and glass beads. The artifacts were so significant that they were later designated as Important Cultural Properties of Japan.

Due to wartime conditions, the jar burial was reburied after the initial discovery. It was not until 2007 that the Karatsu City Board of Education conducted a thorough re-excavation, guided by detailed records left by the scholar-monk Ryukei Kenryo, who had documented the original find. This re-excavation confirmed the location of the royal tomb and revealed additional artifacts, including fragments of mirrors and bronze ornaments that physically joined with pieces found in 1944. New discoveries included jade curved beads (magatama), jasper tubular beads, Chinese-made glass beads, and a Chinese-style ring-pommel sword (sokantonotachi). The total count of glass beads reached an remarkable 2,307 pieces.

The sheer quality and quantity of these grave goods — items sourced from China, the Korean Peninsula, and various parts of Japan — strongly suggest that the person buried here was a chieftain of the highest status, most likely the ruler of the Matsuro kingdom mentioned in ancient Chinese chronicles.

Why These Sites Were Designated as a National Historic Site

The Karatsu Matsuura Tomb Group was designated as a national historic site because these four sites together provide an unparalleled view of how burial customs evolved on the Karatsu Plain throughout the Yayoi period. The dolmen sites (Hayamajiri, Otomo, and Morita) document the earliest adoption of continental burial practices from the Earliest to Early Yayoi period, while Sakuranobaba reveals the emergence of powerful chieftain burials in the Late Yayoi period.

The sites collectively demonstrate how the Karatsu Plain served as a crucial gateway for cultural exchange between the Korean Peninsula and the Japanese archipelago. They show the entire trajectory from the initial reception of foreign burial customs to the development of a socially stratified society with elite rulers who maintained diplomatic and trade connections with the Chinese Han dynasty and beyond.

Highlights and What to See

While the archaeological sites themselves are outdoor locations without elaborate visitor facilities, they offer a contemplative and rewarding experience for visitors interested in ancient history. At Hayamajiri, you can see the remaining dolmen stones in their original hillside setting, imagining how Yayoi-period communities gathered to honor their dead more than two thousand years ago.

For a deeper understanding of the artifacts, visitors should plan a trip to the Matsuro-kan Museum (末盧館), located at the nearby Nabatake archaeological site. The museum displays artifacts from across the Karatsu area's Yayoi-period sites and features dioramas, video presentations, and a restored archaeological park with reconstructed pit dwellings and Japan's oldest paddy fields. Artifacts from the Sakuranobaba Site, including the Important Cultural Property bronze mirrors and ornaments from the 1944 discovery, can be viewed at the Saga Prefectural Museum in Saga City.

The natural setting of these sites also holds appeal. The Karatsu Plain, framed by Karatsu Bay and the green hills of the Higashimatsuura Peninsula, offers scenic beauty that helps visitors appreciate why ancient peoples chose this area as their home and resting place.

Surrounding Attractions

The Karatsu area offers many additional points of interest for visitors. Karatsu Castle (唐津城), built in the early 17th century, provides panoramic views of Karatsu Bay and the Niji-no-Matsubara pine grove — a 4.5-kilometer stretch of black pines along the coast that is designated as one of Japan's top three pine groves. The castle town retains its historic charm, with well-preserved merchant streets and the annual Karatsu Kunchi festival held every November.

Nearby, the Nabatake Site (菜畑遺跡) is recognized as the location of Japan's oldest confirmed paddy field, demonstrating that the Karatsu area was at the forefront of the agricultural revolution that transformed the Japanese archipelago. A visit here complements the tomb group sites perfectly, providing context about the daily lives of the people whose burial customs you have been exploring.

For those interested in ceramic arts, Karatsu is also famous for Karatsu-yaki pottery, a tradition with roots stretching back over four hundred years. Several workshops and galleries are open to visitors, and some offer hands-on pottery experiences.