Israel has been Silicon Wadi since long before the invention of the microchip.

The discovery of a large Roman-era glassworks in northern Israel has shattered archaeologists’ understanding about glassmaking in the region, helping prove that ancient Judaea was a major producer of glass at the time.

The remnants of the 4th century CE factory were unearthed last summer just east of Haifa during construction of a new rail line connecting Afula and Beit She’an to Haifa, the Israel Antiquities Authority announced Monday. Archaeologists said that the site was the oldest known glassworks found in the country, providing the “ultimate evidence” supporting historical references to a Judaean glass industry in Roman times.

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The kilns were discovered adjacent to a contemporary site known as Khirbet ‘Asafna, which was excavated by Missouri University and the Corning Glass Museum in the 1960s and found to contain a workshop for producing glass vessels from the same period.

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Abd al-Salam Sa‘id, an IAA inspector, visited the construction site and noticed “chunks of glass, a floor and an ash layer inside a trench.”

“We exposed fragments of floors, pieces of vitrified bricks from the walls and ceiling of the kilns, and clean raw glass chips. We were absolutely overwhelmed with excitement when we understood the great significance of the finds,” he recounted.

Before the discovery of these kilns at the base of Mount Carmel, the oldest glass manufacturing site in Israel was at Apollonia, from the 6th or 7th century CE.

An ancient glass industry in the Roman province of Palestina was mentioned in historical sources contemporary to the kilns recently found. Monuments erected across the empire by Roman Emperor Diocletian in 301 CE bearing an edict establishing wage and price limits mention vitri iudaici — a naturally green-colored glass made in Judaea. The dictate ordered that a pound of Judaean greenish glass was set at 13 denarii, and plain glass cups and vessels were 20 denarii a pound. Alexandrian glass goods were slightly more valuable.

After the discovery of a copy of Diocletian’s Edict in Turkey in the early 1970s, British archaeologist Dorothy Charlesworth insisted the text was “extremely vague” and posited the Judaean glass was from “the Sidon area” of modern Lebanon.

Scant direct evidence of Judaean glass’s manufacture had been found until now, though Yael Gorin-Rosen, head of the IAA’s glass department, said that chemical analysis of glass objects from across the Roman Empire from this period pointed to their production in Judaea.

“Now, for the first time, the kilns have been found where the raw material was manufactured that was used to produce this glassware,” she said in a statement.

“This is a very important discovery with implications regarding the history of the glass industry both in Israel and in the entire ancient world.”

Professor Ian Freestone of University College London, a specialist in ancient materials, said that about 90% of the raw glass produced in the Roman Empire at the time came from Egypt and Israel.

Because of its low iron content, “the quality of the sand on the coast makes it particularly suitable for glass manufacturing,” Freestone told The Times of Israel.

Mixed with sodium carbonate shipped to Haifa Bay from Egypt, the raw glass manufactured in Judaea was “slightly greenish” and not as high-end as clear Alexandrian glass, but it was nonetheless superior to glass produced elsewhere. It would have been used particularly for windows, he said.

Blocks of greenish Judaean glass would then have been shipped across the empire to be crafted into glasswares and windows.

The find is far from being the oldest glassworks in the world, however. A site in the Nile Delta found in 2005 showed that glass was produced in ancient Egypt as far back as 1250 BCE.