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Glass Made in Asuka: The Asukaike Workshop and a Thousand Years to Home Production

Published October 25, 2026

For a long time, glass was something that came from across the sea. At the end of the Asuka period, the Asukaike workshop in Asuka Village began to make it from raw materials, the first primary glass production in Japan. Where did the skill come from, and what was the glass used for? We follow the excavated finds.

Five clay crucibles shaped like artillery shells and four round lids with handles — Crucibles and lids used to melt glass

Glass from overseas

Glass reached Japan around the 3rd century BCE, in the Yayoi period. For a long time after that, glass was either obtained ready-made from abroad, or imported glass was melted down and reshaped into beads. Primary production, making glass itself from stone and minerals, did not take place in Japan.

Lead glass from Baekje

From around the start of the 7th century, glass rich in lead began to circulate again. Unlike the lead glass of the Yayoi period, it contains no barium, and its raw materials came from a different source. Analysis of lead isotope ratios, which differ from one source to another, suggests it was made in Baekje on the Korean Peninsula.

At the Wanggung-ri site in Iksan, where Baekje had its capital, raw materials for glass, tools such as crucibles, lids and molds, and fragments and finished pieces have been found together. Their composition largely matches the glass used in Japan at the same time, so the site is thought to be one of the suppliers.

Small beads of this period were mostly made by winding molten glass around a core. This replaced the method common until the late 6th century, in which glass drawn into a tube was cut into pieces. Pottery coated with a green glaze, which uses the same raw materials as glass, also became more common at this time.

An early workshop at the Ishigami Site

On green cloth lie quartz, a mold for glass beads, rock crystal, an amber bead and a piece of tortoiseshell; two pottery fragments sit on a black stand to the right — Finds from the Ishigami Site: quartz, rock crystal, amber, tortoiseshell and a mold for small glass beads (upper right)

The Ishigami Site, northwest of Asuka-dera, is thought to be the remains of a facility for entertaining foreign envoys. A layer laid down to level the ground in the early 7th century yielded molds for small glass beads, along with quartz, feldspar, rock crystal, amber and tortoiseshell. A bead workshop seems to have been working nearby before Asukaike.

Two pieces of green-glazed Chinese pottery were also found here. They are thought to imitate metal or glass vessels, and offer a clue to how glass vessels were traded at the time.

The fall of Baekje and the refugee craftsmen

In 660 Baekje was destroyed by the allied armies of Silla and Tang China. Around that time, members of the royal family and many others fled to Wa, as Japan was then known. Descendants of the royal family later served the court as the Kudara no Konikishi clan, and craftsmen put their skills to work in many places. The craft of glassmaking is thought to have reached Asuka with these people.

The Asukaike workshop: Japan's first primary glass production

The Asukaike site lies just southeast of Asuka-dera, where the Nara Prefecture Complex of Man'yō Culture now stands. It was identified in 1991 in an excavation before Asukaike, an Edo-period irrigation pond, was filled in, and turned out to be a workshop of the late 7th to 8th centuries. It is now a national historic site.

The workshops were concentrated in the southern part of the site and produced a wide range of goods: gold, silver, copper and iron, glass, rock crystal, amber, tortoiseshell, woodwork, lacquerware and lead-glazed pottery. Glass was one of them, and here lead glass was made from raw materials for the first time in Japan.

On green cloth lie lumps of clay molds, a bead mold full of holes, tiny pressed glass pieces, and quartz, feldspar, galena, amethyst and rock crystal — Clay molds, molds for small glass beads, pressed glass, and raw materials such as quartz, feldspar and galena

The minerals found were quartz, feldspar and galena, an ore of lead. This combination shows that lead glass was being made. The lead ore was mined at the Naganobori copper mine in Yamaguchi Prefecture, which appears to have been opened in the early 7th century. Where the quartz, feldspar and coloring agents came from is not yet known.

The shell-shaped crucibles and lids closely resemble tools from Wanggung-ri in Baekje, yet they were made with techniques native to Japan. It suggests craftsmen from Baekje and local artisans working side by side in the same workshop.

Small beads, and round beads with no hole for a string, were made by pouring glass into molds. An unusual find is the so-called stamped glass: small oval pieces with a raised center, thought to have been made by pressing beads into a mold.

About a thousand years after glass first arrived in the 3rd century BCE, it was here at Asukaike that glass could finally be made from raw materials.

Cloisonné from the Kengoshizuka Kofun

On a black stand: four hexagonal fittings (bottom row), three reproductions colored green and brown (middle row), and strings of glass beads and flower-shaped fittings above — Cloisonné hexagonal fittings from the Kengoshizuka Kofun (bottom) and reproductions (middle)

The Kengoshizuka Kofun, which became part of the World Heritage site "Asuka-Fujiwara" in 2026, has also yielded objects made with glass. Among the fittings attached to the coffin are hexagonal ornaments decorated in cloisonné.

Each has a flower-shaped partition set on a hexagonal metal base like a tortoise shell, with glass coloring both inside and outside the flower. They are the oldest cloisonné objects in Japan and an Important Cultural Property. Analysis shows the glass was made with lead from the Korean Peninsula.

So at roughly the same time as Asukaike began making domestic lead glass, the coffin in a tomb thought to be an imperial one was adorned with glass made from Korean lead.

Glass after Asuka

Later, glass objects came to be made in many places, centered on the capitals of Fujiwara-kyō and Heijō-kyō. Glass from abroad did not stop coming either: in the Nara period, domestic glass, imported glass and pieces handed down from the Kofun period were all in use. Such glass still survives among the treasures of the Shōsōin.

The green-glaze technique, too, led on to Nara sansai ware and the green-glazed pottery of the Heian period.

Seeing it today

The Nara Prefecture Complex of Man'yō Culture stands on the Asukaike workshop site, and parts of the remains can be seen inside and outside the building. The Ishigami Site and the Kengoshizuka Kofun are also in the village and can be visited on the same walk.