Nakahara Ruins

A Jōmon Village Built of Coral Stone

About twenty-five hundred years ago, on a small island in what is now Okinawa, a community of roughly two dozen households dug shallow pits into the coralline soil, ringed them with walls of cut limestone, and roofed them with thatch. The settlement was eventually abandoned, the depressions filled with reddish earth, and the land turned over to sugarcane. Then, in 1978, a survey conducted ahead of a land-improvement project on Ikei Island uncovered the foundations of 23 dwellings — the largest known prehistoric village ever found in Okinawa Prefecture. Today the Nakabaru Site preserves that village in reconstructed form, and remains the prefecture's first archaeological settlement to be rebuilt for public visitation.

Ikei is the easternmost of four islets strung off the Katsuren Peninsula on Okinawa's central east coast. Local people call it Ichi-hanari, meaning "the island that is farthest away." The Nakabaru Site sits near its geographical center, on a flat plateau roughly 24 metres above sea level, with low fields of sugarcane on every side and a screen of windbreak trees ringing the grounds.

From Sugarcane Field to National Historic Site

The 1978 discovery was a genuine surprise. Researchers had been carrying out a routine investigation before farmland improvements when they began turning up postholes, hearths, and coral-block walls in the subsoil. Excavation eventually exposed 23 building remains across a zone measuring roughly 200 metres east-to-west by 100 metres north-to-south. The dwellings fell into two distinct sizes: larger ones around 5 to 6 metres across, and smaller ones of 2 to 3 metres, arranged as if smaller structures clustered around a central main house. That spatial pattern offered the clearest picture yet of how a late Jōmon community in the Ryukyus actually organised its village.

The recovered pottery proved important enough that archaeologists named a type after the site itself. Nakabaru-shiki pottery, including pointed-bottomed deep bowls and jar forms, became a reference standard for late Jōmon ceramics in the southern islands. Alongside the pots came stone axes, grinding stones, bone needles and awls, the bones of fish and game, and small beads cut from imo (cone) shells. The remains of an adult woman were found inside the first house excavated, suggesting that disused dwellings sometimes served as burial places for those who had lived in them.

The Agency for Cultural Affairs designated the site nationally on 16 August 1986. From 1987 through 1996, Uruma City and the prefecture carried out a decade-long programme of conservation and reconstruction, opening the site to visitors under the name Ichi-no-Sato Nakabaru Iseki.

Why the Walls Are Made of Stone

The detail that distinguishes Nakabaru from mainland Japanese pit-dwelling sites is immediately visible. Across the rest of the archipelago, late Jōmon houses typically rest directly in an earthen pit with wooden posts rising from the floor. Here, the inhabitants quarried Ryukyu limestone — the porous coralline rock that underlies most of these islands — and stacked it into low walls along the inside of the pit. The roof was then thatched over this masonry base. The arrangement makes structural sense in a subtropical climate prone to typhoons: the stone weighs down and braces the lower walls, while the porous rock allows air to circulate, keeping the interior cool in summer and surprisingly warm in winter.

When the reconstruction work was carried out, the team turned to materials that would have been locally available in the Jōmon period. The posts and rafters were cut from yarabu (also known as terihaboku, an Okinawan species of mast tree), with bamboo lashings and chigaya grass thatch covering the roof. Cordage was twisted from the aerial roots of adan, the spiky pandanus tree that still lines the island's beaches. Walking among the rebuilt houses, you can crouch through a low entrance and feel the temperature drop several degrees.

What to Look For on a Visit

Ten reconstructed pit houses now stand on the original house-foundation marks, separated by mown paths. The largest, labelled House No. 15, measures about 5 metres on each side and has a sunken floor depth of 48 centimetres; archaeologists identified the remains of a hearth here and have interpreted it as the central building of the village. Smaller satellite dwellings nearby give a sense of the household clustering pattern revealed by the excavation.

The setting itself is part of the experience. Because Ikei Island is so flat, planners ringed the site with mature windbreak trees, partly to shield the thatched roofs from typhoon winds and partly to recreate the wooded environment that would have surrounded the original village. In late summer the surrounding sugarcane reaches above head height, and the cicadas in the windbreak can be deafening. A signposted path leads down toward the coast and the spring known as Innagā (also called Inunaga), a natural water source whose name is said to come from an old story of a damp dog that emerged from the cliff during a drought. The spring is believed to have supplied the Jōmon villagers as well.

The site is unstaffed and free to enter. A small monument carved in the shape of a stone axe stands near the entrance, recalling one of the most distinctive of the recovered artefacts. There is no visitor centre, no admission booth, and only basic toilet facilities; visitors who want to see the pottery, beads and human remains in person will need to visit the prefectural and city museums on the main island.

Around the Site

Getting to Nakabaru is half the pleasure. From Okinawa City, the route runs east to the tip of the Katsuren Peninsula and then out across the Kaichū-dōro (literally "sea road"), a five-kilometre causeway that crosses open ocean to Henza Island. The road continues through Henza, over Miyagi Island, and across the final span of the Ikei Bridge, with limestone cliffs and turquoise shallows visible on either side. The drive from Naha takes about an hour and forty minutes; from the Okinawa-Kita interchange on the expressway, allow roughly forty minutes.

Once on Ikei, the island rewards lingering. Ikei Beach, a sheltered inlet on the eastern shore, offers calm swimming and snorkelling in some of the clearest water near the main island. Ohtomari Beach, on the north end, is a quieter natural strand with white sand. Crossing back to Miyagi Island puts you within reach of Kafu Banta, a dramatic 100-metre limestone cliff overlooking the East China Sea, while Hamahiga Island (accessible by a separate bridge) is home to the Amamichū tomb, sacred to one of the legendary ancestral couples of Ryukyuan creation mythology. A full day on the causeway islands easily combines prehistory, beach time, and dramatic coastal scenery.