Temple Ruins

A Jōmon Jade Workshop Above the Sea of Japan

The Teraji Site occupies the tip of a low hill in Itoigawa, at the western edge of Niigata Prefecture, where the land slopes down toward the Sea of Japan. It lies roughly halfway between the mouths of the Himekawa and the Ōmi rivers, in a stretch of coast that holds a particular distinction: the Itoigawa area is the only natural source of jadeite in Japan. People settled on this hill during the Middle Jōmon period and kept returning to it until the Final Jōmon, a span of well over two thousand years. They came for one reason above all. They worked jade here.

What sets Teraji apart is not a single building or a famous object but a long sequence. Generation after generation built pit-dwelling workshops on the same ground, gathering jadeite pebbles from the rivers and beaches below and grinding them into beads. Then, toward the end of that occupation, the inhabitants laid out something quite different: an arrangement of standing stones and four enormous wooden posts that speaks of ritual rather than craft. The site was designated a National Historic Site on 5 December 1980.

From a Land Survey to a Discovery

Teraji came to wider notice almost by accident. In 1967 the hill was marked for a land readjustment project, and rescue excavation began ahead of the construction work. Five separate digs followed through 1973. They uncovered six pit dwellings interpreted as jade-working workshops, together with the unusual stone feature on the lower ground to the east.

To understand why so much jade passed through this spot, it helps to look upstream. The middle reaches of the Himekawa and its tributary the Kotaki, and the upper course of the Ōmi River, carry jadeite down from the mountains. The current rolls the stone into rounded pebbles and deposits it along riverbeds and on the gravel beaches of the coast. The Jōmon people of Teraji did not mine jade. They picked it up. Raw pebbles collected from the rivers or the shore were carried back to the hill, shaped, and polished into ornaments that eventually reached communities across the Japanese archipelago.

Jadeite is an exceptionally hard stone, and working it without metal tools was slow, patient labour. The craftspeople of Teraji relied on hammerstones to rough out a shape and sandstone whetstones to grind and polish it. Alongside the jade, they also produced polished axes from serpentine, the rock that often hosts jadeite in the same mountains. The two industries ran side by side on this single hilltop for centuries.

Why the Site Was Designated

Teraji earned national protection for two reasons that rarely appear together. First, its workshops document the practical reality of Jōmon jade production in unusual detail. Second, its Final Jōmon stone arrangement records a distinctive local form of ritual. One half of the site explains how a community made things; the other half hints at what it believed.

The workshop evidence is concrete. Excavators recovered jadeite pebbles still in their natural state, finished ornaments, and many half-worked pieces abandoned partway through production. That mixture is the signature of a working site rather than a place that simply received finished goods. The presence of unfinished serpentine axes and stone flakes confirmed that axe-making went on here as well. Few Jōmon sites preserve the full chain from raw material to finished object so clearly, and Teraji helped establish that the jade circulating through prehistoric Japan was domestic in origin.

What to Look For

The most fully excavated of the dwellings, known as Pit Dwelling I and dating to the early Middle Jōmon, was a circular pit about five metres across. A terrace fifty to seventy centimetres wide ran along the inner wall, and a square stone-lined hearth sat near the centre. The detail that matters most to the story is small and easy to miss. A large flat whetstone had been buried in the floor next to the hearth, and against the terrace wall lay a shallow circular pit filled with fine sand, beside a flat riverstone bearing a sandstone whetstone. This was not a tidy display. It was a workbench, fixed into the ground, where someone sat and ground jade.

The stone arrangement on the lower ground is the site's strangest feature. It spreads roughly twelve metres east to west and sixteen metres north to south, built from standing stones that mark out divisions and flat riverstones that pave the spaces between. Four elements stand out: an oval ring of stones to the northwest, a square setting that once held four wooden posts about sixty centimetres thick, a triple arc of stones to its south, and a hearth-like ring at the centre. Stone rods were set at three corners of the four-post square, and inside it excavators found a ritual implement and several combs finished in red lacquer. The central ring yielded the bone fragments of more than ten individuals. Visitors today see a quiet grassy field rather than the bones and posts, but knowing what the ground once held changes how it feels to stand there.

Visiting Teraji and the Coast Around It

The site is now maintained as an archaeological park. One pit dwelling has been reconstructed, and trees of the kind that grew here in the Jōmon period have been planted across the grounds, so the park gives a sense of the prehistoric setting rather than a row of foundations. The excavated finds, including jadeite pebbles and half-worked beads, are kept and displayed at the Ōmi Natural History Museum nearby.

Teraji sits within the Itoigawa UNESCO Global Geopark, and the coast a short distance away rewards a detour. The gravel beaches between the Himekawa and Ōmi rivers are among the few places in the world where jadeite washes up naturally, and the stretch known locally as Lavender Beach takes its name from the pale violet jade occasionally found there. Walking that shoreline and turning over pebbles is, in a real sense, repeating what the people of Teraji did five thousand years ago.

For a fuller picture of the region's Jōmon jade culture, the Chōjagahara Site, another National Historic Site with its own reconstructed dwellings and a museum, lies elsewhere in Itoigawa. The Fossa Magna Museum explains the geology that made the jade in the first place. Itoigawa is reached in about two hours from Tokyo by the Hokuriku Shinkansen, which makes a visit straightforward to plan.