Mystery of the Plain of Jars
The quest to solve one of archaeology’s greatest puzzles
Archaeologists still don’t understand the purpose of a mystical 2000-year-old collection of large stone containers.
Shafts of sunlight
struggle to penetrate the mist hanging over the forest on a mountaintop in the northern reaches of the Annamite Range in Laos. It’s a cold day in February 2017 and a metal pot of coffee simmers on a fire. Nearby, archaeologist Dougald O’Reilly, in a canvas stockman hat and army pants, black puffer jacket and Grateful Dead T-shirt, is crouched in a precisely cut, four-by-four-metre trench. At its edge is an oval stone disk roughly one metre across. It’s lying flat near a huge stone ‘jar’.
This is Site 52 of the Plain of Jars, so named for the plateau where the best-known group of jars, Site 1, is situated, near the city of Phonsavan. From Phonsavan, Site 52 is an hour’s drive on a paved road, then another 45 minutes up a precipitous dirt track. Scattered all around this forest f loor are some 400 stone vessels, one to three metres tall, some lying on their sides. A number of the jars are broken, with trees growing through them; a few disks, some of them perhaps lids, can be seen too. The jars are empty except for stagnant rainwater and spiders.
O’Reilly, 53, is an assistant professor at the Australian National University and chief investigator on this three-week field trip – part of a five-year effort to solve the mystery of the jars. “The two most common questions I get are, ‘What were the jars for, and how old are they?’” says the dark- haired, blue- eyed O’Rei l ly. “That’s what we’re trying to find out.”
It’s a team effort that includes O’Reilly and his project partner, fellow archaeologist Louise Shewan of the University of Melbourne, together with Lao government and archaeologists led by Dr Thonglith Luangkoth,
director of archaeology with Laos’s ministry of information, culture and tourism. “We couldn’t do this research without some amazing people on the ground,” adds O’Reilly.
One of their main goals in this project – the first of its scale in some 80 years – is to map the sites and the jars with remote sensing and GIS ( geographic information systems) technology.
This proved crucial in Laos’s bid for UNESCO World Heritage status for the jar sites two years later. Laos is one of the world’s poorest countries, so the World Heritage status is hoped to boost tourist numbers and preserve the jar sites.
LITTLE IS KNOWN
about the megaliths, which are thought to have been made a couple of thousand years ago. There are some 80 jar sites scattered around northeast Laos, and a handful in remote eastern India, thousands of kilometres away. Many were quarried a few kilometres from where they sit, further adding to the Stonehenge-like mystery: weighing as much as ten tonnes apiece, how did
they even get here from the quarries? Were they transported on log rollers, dragged by elephants, or somehow rolled to the sites? O’Reilly calls the search for answers “invigorating”.
No major excavation has been done since the 1930s, when famed French archaeologist Madeleine Colani first studied these jars in what was then part of French Indochina. Then, in the 1940s came civil war and later the Vietnam War, during which the US bombed Laos for a decade. It’s said Laos is the most heavily bombed country per capita in history. About 30 per cent of the 260 million bombs dropped never detonated, so the unexploded ordnance, or ‘UXO’ has been a deadly obstacle – not just for archaeological work, but for everything from road building to farming. The British non-profit Mines Advisory Group (MAG) has been in Laos since the mid-1990s to remedy that. It’s slow, painstaking work, but the group has now cleared UXO from various locations for a total of about 60 square kilometres, indicating cleared areas by embedding the ground with bricks engraved ‘MAG’. It has helped keep about one million people safe.
Site 1 was declared clear about ten years ago. During the 2016 excavat ions of that bomb- cratered plateau, home to some 300 jars, the archaeology team found human bones in smaller ceramic vessels buried underneath flat stone disks beside the jars. The theory is that the jars were for mortuary practice. “The people of perhaps the Iron Age – 2000 years ago – might have used them to rot their dead, then later transferred the bones to the smaller vessels for burial,” says O’Reilly. Archaeologists including Colani (whom O’Reilly admires so much he named his daughter, Madeleine, after her) and Julie Van Den Bergh, a Belgian who mapped some of the jar sites in the early 2000s, believed this. “But until we get lab results from samples we’ve taken, that remains unproven,” says O’Reilly. So far there aren’t really any other plausible theories. A fanciful one is that some villagers believe the jars were used to store rice wine for a mythical giant.
Back at Site 52, which had no UXO, only machine-gun shells, eight of O’Reilly’s and Shewan’s team members have been using mattocks – pickaxe-like tools – to dig a precise
“IRON AGE PEOPLE MIGHT HAVE USED THEM TO ROT THEIR DEAD, THEN TRANSFERRED THE BONES TO THE SMALLER VESSELS FOR BURIAL”
trench into the crumbly red soil beside an oval disk. They want to see what’s underneath; O’Reilly suspects human bones, as at Site 1. But the disk is thicker than expected – about 25 centimetres – and too heavy to lift without the help of levers. O’Reilly walks off into the forest with his machete, cuts a couple of tree limbs and drags them over.
As they use the levers to lift the lid, the moment of truth reveals … nothing. They take a few more hours to dig down another third of a metre or so – and still nothing.
“Oh, that’s very interesting,” remarks O’Reilly dryly, rubbing his chin in faux contemplation. Sure, he’s disappointed, as is the team, but “sometimes you find things, sometimes you don’t,” he says with a shrug. He’s been doing this kind of work for more than 25 years, including leading an excavation in Cambodia at the 12th century Angkor Wat – the world’s largest religious complex – at which he and his team made a major discovery in 2010, another temple underneath. “Even when what you’re hoping for isn’t there, in this case anthropogenic material, it’s still about gathering information. And you just keep going.”
OVER THE THREE WEEKS
at Site 52, the team didn’t find bones but, significantly, they discovered four
previously unknown quarry sites. They also tried a new type of testing. In simple terms, says Shewan, stone can’t be dated, “so we took core samples from the bottoms of the jars for ‘optically stimulated luminescence’ testing.” They hope it will reveal when the jar bottoms were last exposed to sunlight – therefore, when they were placed on the ground where they sit. The process of taking those stone samples was tricky, as no light can be present: black lightproof tarpaulins were tented over the extraction site, and O’Reilly held a torch covered in a red filter while he used a drill to extract the core.
Back at their base in Australia, O’Reilly and Shewan can ‘visit’ Laos any time they like thanks to the CAVE2 3D facility at Monash University in Melbourne. Drone photos gathered in 2016 have been used to create a virtual Site 1. They also collected drone photos at Site 52. CAVE2 is the world’s largest virtual reality facility of its kind – no VR goggles required. “We can return to our excavations to do things like take measurements and interpret data,” says O’Reilly. And thanks to drones, they’ll have a safe way to check out jar sites that may not yet be clear of UXO. “Of course, you can’t excavate without being there, but you can gather a lot of information on site location and the surrounding landscape.”
It could be a year until the team has results from soil and other physical samples – including a human tooth – that they gathered at Site 52, and up to two years for the optically stimulated luminescence results. But O’Reilly hopes the data will finally provide some answers about these massive megal iths on remote mist- shrouded mountaintops. “Archaeology,” says O’Reilly, “is largely about untangling mysteries, and the Plain of Jars is one of the world’s enigmas.”