Dotted with thousands of giant stone vessels, the Plain of Jars in Laos is one of the most intriguing archeological sites in Southeast Asia. Now, a new study has uncovered how old the jars are, and it turns out they’ve been there much longer than previously thought.
The Plain of Jars extends across the Xiangkhoang Plateau, made up of over 100 sites containing anywhere from a few to a few hundred jars. The jars themselves are hewn from stone, stand between 1 and 3 meters tall, and weigh up to 20 tonnes. Their purpose has been debated for decades, with some suggesting they may have been used to store water or brew alcohol, while the presence of human remains implies they hosted burial and/or cremation rituals.
A few years ago, a team of archeologists from Australian National University (ANU) found a series of new jar sites, and now members of the same team have made a new discovery: how old the relics may be.
In excavations conducted in early 2020, the team took samples of sediment from underneath jars in two sites. These were then analyzed using Optically Stimulated Luminescence (OSL), a technique that can determine how long it’s been since the grains were exposed to sunlight.
Previously the jars had been dated generally to the Iron Age, between 500 BCE and 500 CE. But the team’s analysis found that they had been sitting there much longer – anywhere from 1240 to 660 BCE.
“With these new data and radiocarbon dates obtained for skeletal material and charcoal from other burial contexts, we now know that these sites have maintained enduring ritual significance from the period of their initial jar placement into historic times,” says Dr Louise Shewan, co-lead researcher on the study.
The team also used a process called detrital zircon U-Pb dating to determine where the jars originally came from. They took sandstone samples from jars in Site 1, and compared them to samples from a nearby sandstone outcrop and a half-finished jar in what’s believed to be a quarry, about 8 km away. The zircons appeared to be around the same age, indicating that the outcrop was a likely source for the stone used to make the jars.
“How the jars were moved from the quarry to the site, however, remains a mystery,” says Dougald O’Reilly, co-lead researcher on the study.
The scientists plan to continue studying the jars, with the aim of taking samples from other sites.
The research was published in the journal PLOS One.
Source: University of Melbourne
