The discovery of pre-Angkorian ironworks sites in Preah Vihear province in 2010 is a tale of perseverance with a measure of luck, as is so often the case with important archeological finds.

For years, archeologist Thuy Chanthourn had been exploring the countryside along the path of an Angkorian-era road that linked Preah Vihear temple and the Stung Treng City area, hoping to find the site of a large settlement named Mlu Prei mentioned decades ago in an obscure French research document.

In 1943, Paul Levy of the French research institution Ecole Francaise d’Extreme-Orient had published a report on that settlement that some historians believed was the area’s major center 1,500 years ago.

But all Mr. Chanthourn had been able to find of this center were a few houses and a shaky wooden footbridge over a stream in Preah Vihear province.

Mr. Chanthourn usually conducted his research on his own time. But in January 2010, he took with him 10 of his archeology students from the Royal University of Fine Arts. After crisscrossing the region for hours along jungle trails, at 4:30 pm on January 14 he and his students reached the site of road construction complete with work crews and heavy machinery. An oxcart road that had been a major thoroughfare in Angkorian times was being turned into a drivable road thanks to Chinese funding.

While they watched, a bulldozer dug into the ground and lifted some odd-colored earth, which puzzled Mr. Chanthourn.

“It was really dark earth, almost like coffee…and small stones as black as onyx,” he said. And then he and his students noticed fragments of clay pots and smelted iron.

Mr. Chanthourn immediately asked the workers to stop work. “I asked them, ‘please give me some time to check,’” as this could be an iron smelter site so far unknown to archeologists, he said. Workers agreed, and followed his suggestion to work a kilometer away from that particular site, he said.

Mr. Chanthourn then called their manager and Chheb district authorities so that he could explain the situation. Within 15 minutes, district governor Oun Vuthy was at the site, asking him to draw a map of the zone that he felt should be protected so it could be sent to Preah Vihear provincial governor Oum Mara. Mr. Chanthourn complied and asked that the site be left untouched until the morning so that he and his students could investigate.

“I was a little bit scared, a little bit happy, a little bit nervous: After all, I had just stopped a government project,” the 41-year-old archeologist explained.

“The next day, I got a phone call from Deputy Prime Minister Keat Chhon—would you believe? The deputy prime minister called me in the jungle,” he said. Deputy Prime Minister Sok An had tried to reach him as well but was unable to do so due to poor phone coverage, and had asked Mr. Mara to contact him on his behalf.

And then officials from several ministries arrived at the site along with government television news crews. Unbeknownst to Mr. Chanthourn, Mr. Mara had faxed Prime Minister Hun Sen who had alerted several ministries and asked them to immediately investigate.

Officials all agreed on the importance of the site, and the archeologist received government support to conduct an archeological excavation with a team of students and workers.

Mr. Chanthourn, who had spent three months each year from 1999 through 2002 studying excavation techniques in Germany, went to work.

He and his team excavated in 2011 and again in 2012. In addition to hundreds of small sites, they were able to identify five major sites of ironworks: the first one spotted in Chheb district, two in Rovieng district, one in Sangkum Thmei district in Preah Vihear province, and one in Anlong Veng district in Oddar Meanchey province.

The researchers not only found pieces of smelted iron—at times on the very surface of a site—but also pieces of pipes used in smelters and of course iron ore.

The available resources enabled them to dig three meters and, using thermoluminescence, known as TL, dating technique, they were able to officially date the sites as being 1,200 years old. However, Mr. Chanthourn believed that digging to a depth of six meters would show the sites to be much older, and he hopes to be able to do so in the near future.

The five sites indicate major industrial operations that shed light on some features of the Angkorian era. The wall sculptures on the Bayon temple for instance show Khmer leaders riding chariots and soldiers equipped with weapons and shields, suggesting an ample source of iron to produce such items, which the site excavations confirmed, Mr. Chanthourn said.

Moreover, iron artifacts found near one site show that iron bars were used to consolidate stones in temple construction. These ironworks sites indicate that, with iron being so readily available, the use of iron bars and joints in temple construction might have been widespread.

Popular belief in Cambodia is that the Kuy minority specialized in ironworks centuries ago, which may actually have been the case, Mr. Chanthourn said. But since so little is known about life during Angkor, one cannot say with certainty whether this was the case or how this important industrial sector operated, he added.

Archeological artifacts that Mr. Chanthourn and his team collected on their dig are now on exhibit at the Eco-Global Museum near the Preah Vihear temple.

Today, Mr. Chanthourn’s main concern is that the archeological sites he has uncovered be preserved, especially since speculation has begun on land in those areas. Moreover, on December 31, Cambodia Iron and Steel Mining Industry Group and China Railway Group signed a memorandum of understanding to build an iron mill in Preah Vihear province, which may soon involve major industrial activity in the province.

For Preah Vihear provincial governor Oum Mara, however, protecting the archeological sites goes without saying.

“The iron smelter sites need to be preserved as future tourism destinations and for future research and excavation…having great importance in terms of heritage for the nation as a whole,” he said. “The next step is: We need to list the area as a protected site and we hope to develop it into a heritage area for the country.”

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