Oyamazaki Tile Kiln Site

The Kilns That Roofed a Capital

In 2004, a routine survey ahead of a housing development on a low hillside in Ōyamazaki turned up something the developers had not expected: a row of clay-lined pits cut into a slope, each ringed with a thick layer of ash and broken roof tiles. Archaeologists from the Ōyamazaki Town Board of Education recognised the pits as kilns. Within little more than a year the ground was protected as a National Historic Site, designated on 26 January 2006. Continued excavation has since brought the count of identified kilns to twelve.

The Ōyamazaki Tile Kiln Site (Ōyamazaki Kawaragama-ato) sits at the southwestern edge of Kyoto Prefecture, in the town of Ōyamazaki in Otokuni District. It dates to the early Heian period, the eighth to ninth centuries, and it was a state-run workshop. Its job was to make roof tiles for the new imperial capital of Heian-kyō, founded in 794, and for the palace at its centre.

Why a Tile Kiln Became a National Site

Building a capital from open ground required tiles by the hundreds of thousands. No single kiln could supply them, so tile production was spread across many workshops on the hills around Heian-kyō. Ōyamazaki was one of these official kilns, and its location was no accident. The site stood at a junction of land and water routes. Tiles fired here travelled roughly 300 metres to a riverbank, were loaded onto boats, and were carried up the Yodo and Katsura rivers toward the building sites of the capital.

What lifts Ōyamazaki above an ordinary production site is the evidence it preserves about where its tiles went and how the work was organised. Eaves tiles excavated here have been matched to specific buildings: the Chōdō-in, the great hall of state at the heart of the Heian Palace, as well as the Saga-in and the Kaya detached palace. Few kiln sites can be tied so directly to named imperial structures.

Comparing tiles from Ōyamazaki with those from the Nishigamo and Kishibe kilns (the latter in present-day Suita, Osaka) tells a second story. Some of the decorative molds, the carved frames pressed into the clay to give eaves tiles their patterns, were shared between these workshops. That sharing implies that molds and the craftsmen who used them moved from one official kiln to another. At the same time, Ōyamazaki produced tiles from molds found nowhere else, a detail that has revised the accepted picture of how tile supply was managed in the early Heian period.

What the Ground Reveals

The twelve kilns fall into two groups by the direction their fire-mouths face. Five open toward the south; seven open toward the east, and that eastern set divides again into a southern cluster of five and a northern pair of two. The planning behind this layout is unusually clear. Where five kilns form a single unit, their stoking mouths line up in a straight row, spaced at intervals of about six metres, and the kilns themselves were built to nearly matching shape and size. This is not a workshop that grew piece by piece. It was laid out.

Each kiln has the same basic anatomy: a combustion chamber where firewood burned, a firing chamber where the tiles were stacked, and in front of the fire-mouth a flat working area. Along the edge of that working area lay the ash deposit, the spent ash from countless firings mixed with tiles that had cracked or warped and been thrown aside. For an archaeologist these discard heaps are a gift, because the failures reveal the molds, the clay, and the firing temperatures as plainly as the successes.

The kilns turned out a full range of roofing components rather than a single type. Excavations have recovered round eaves tiles and flat eaves tiles, the decorated pieces that finished the edge of a roof, along with broad flat tiles, curved ridge tiles, and ornamental gable-end tiles. Together they amount to a complete tile kit for the kind of formal, tile-roofed architecture that the new capital demanded.

Visiting the Site

The excavated kilns themselves have been reburied. This is standard practice for earthen archaeological remains, which deteriorate quickly once exposed, and it means visitors do not see the original clay structures. Instead the Historic Ōyamazaki Tile Kiln Site Park marks the position and outline of the kilns above ground using ceramic panels and plantings, with one kiln shown at full scale so the dimensions register clearly. Explanatory boards stand at the key points.

The reward of the visit is partly the view. The park occupies high ground, and from its observation plaza the southern half of the Kyoto basin opens out, with the Yodo river plain below and a sweep of hills running from Mount Hiei toward Mount Ikoma. Standing here, the logic of the place becomes physical: the river that carried the tiles is in sight, and so is the direction the capital lay.

The park is open every day, free of charge, though closing time shifts with the season. It is a short, walkable site rather than a half-day destination, and pairs naturally with the other attractions clustered around Ōyamazaki.

Around Ōyamazaki

For its small size, Ōyamazaki carries a remarkable concentration of history. Rising directly above the town is Tennōzan, the hill whose name became shorthand for a decisive contest: in 1582 the forces of Toyotomi Hideyoshi defeated Akechi Mitsuhide here at the Battle of Yamazaki, days after the death of Oda Nobunaga. Walking trails climb the hill past viewpoints.

At the foot of Tennōzan stands Myōkian, a temple that holds Tai-an, a tea room attributed to the tea master Sen no Rikyū and designated a National Treasure. Nearby, the Asahi Group Ōyamazaki Villa Museum of Art occupies an early twentieth-century mountain villa, with a later gallery wing by the architect Tadao Andō, and the Suntory Yamazaki Distillery, Japan's first malt whisky distillery, lies a short walk in the other direction. The Ōyamazaki Town History Museum gives useful context for all of these, including the tile kilns. The site's proximity to two stations makes a day combining several of them straightforward.