Site 1, Xieng Khouang, Laos

Plain of Jars

Jars perhaps set by the late second millennium BCE (burials around them are much later)

On a grassland plateau about 1,100 metres up, stone jars stand in groups, some of them hollowed to a depth you can look into. The listing dates an Iron Age funeral culture from about 500 BCE to 500 CE. A clock in the soil under two jars points earlier, and the human bone buried beside them points centuries later.

Why this is extraordinary

The jars are the first thing. On the Xieng Khouang plateau, hollowed sandstone cylinders stand in the grass, some of them tall enough that the rim is above your shoulder. The World Heritage listing counts more than 2,100 of them, used for funerary practices, and dates that culture from about 500 BCE to 500 CE, possibly as late as 800 CE. Fifteen sites are listed. They hold 1,325 jars, stone discs that may have been lids, quarries, and burials.

So how old is the stone where it stands? A 2021 study looked under the jars, not only beside them. Quartz grains in sediment store a glow that resets when sunlight hits them. Under two jars at Site 2, the top of that sediment last saw the sun between about 1240 and 660 BCE. Human bone buried at Site 1 is much later: one sample about 772 to 950 CE, another about 1046 to 1219 CE. The catch is that a grave dug next to a jar can drop a late piece of charcoal underneath it. One such charcoal, under a jar at Site 1, falls in the twelfth or thirteenth century, with a burial beside the spot. Placement and funeral are not yet one date.

The stone has a source. About 8 kilometres northwest of Site 1, a quarry slope still holds jars left unfinished. The ages of zircon crystals in a broken jar match that rock. Unexploded ordnance from the wars of the last century still keeps people off much of the working face. What this changes: if the glow-dates hold, the jars were already landmarks when the later graves were cut among them. If the listing’s window is the real placement, the earlier glow is the age of the soil and the jars belong with the Iron Age goods. The sources used here do not print a sun or star alignment for the groups, so the room does not invent one.

Why it matters

If the jars and the burials are one rite, this is a cemetery that lasted. If the jars were set first and the graves came long after, the plain was reused, and the listing’s Iron Age window is only part of the story. Either way, the jars had to be cut and moved.

Sandstone. About quartz grains about 7; the cement is softer on the Mohs scratch scale. A higher step scratches a lower one. The bars are not a cutting rate. Diagram: Our Deep History.

Stone and the tools

The jars are carved from sandstone. Quartz, the hard grain, is 7. Iron and bronze tools turn up with the later burials, and the jars themselves are dressed stone, so a metal edge is part of the usual kit. The cement that holds a sandstone together can be much softer than the grains.

The usual account. A quarry with unfinished jars, about 8 kilometres from Site 1, is the published source for that group, matched by the ages of tiny crystals in the rock. Hauling a hollowed sandstone jar across that distance is a crew and a sledge problem, not a stone the tools could not scratch.

The other reading. Soft cement does not lift a jar. What stays open is the size of the crew and the path from the quarry, which unexploded ordnance has kept mostly unwalked. No rate for hollowing one jar is printed in the sources used here.

The World Heritage property is fifteen sites. It holds 1,325 of the jars, plus stone discs that may be lids, quarries, and burials. Across the province the survey counts 2,107 finished and unfinished jars. Site 1, the place in the photograph, has 316 megaliths, most of them sandstone, up to about 2.5 metres high. The plain itself is about 80 square kilometres of poor grassland. The sources used here do not describe a solstice or a star sightline for the jars, so none is drawn.

Photo tour

2 photographs, unedited. On a phone, swipe the row. Choose one to look closely.

What is still unexplained

These sit beside the consensus account, with the same visual weight. None of them is marked solved.

Open A date under the jar, and a date in the grave Sediment immediately under two jars at Site 2 last saw daylight between about 1240 and 660 BCE. That is a limit on when those jars could have been set down, read from a glow stored in quartz grains, not a birthday carved on the stone. Human bone from burials at Site 1 falls in the eighth to tenth centuries CE and again in the eleventh to thirteenth. Charcoal under one jar at Site 1 is as late as the twelfth or thirteenth century, and a burial sits beside that sample, so the charcoal may belong to the grave rather than to the day the jar arrived. The listing’s window, about 500 BCE to 500 CE and possibly to 800 CE, sits between those clocks and does not erase them.

Observed A quarry that still holds unfinished jars Site 21, about 8 kilometres northwest of Site 1, is a slope of about 20 hectares with jars left at every stage from a rough-out to a nearly finished cylinder. The ages of zircon crystals in a broken jar at Site 1 match stone from that quarry. Unexploded ordnance still closes most of the working face, so the path the jars travelled is mapped more than it is walked.

Location and dating

Location: Site 1 on the Xieng Khouang plateau, central Laos. The pin is that group. The other jar sites scatter around the same plain and its spurs.
Period label: Current consensus — open to revision The listing places the funeral culture from about 500 BCE to 500 CE, possibly as late as 800 CE. Placement of jars at Site 2 is read as early as the late second millennium BCE. Mortuary activity around the jars runs, on the bone, from about the eighth century CE into the thirteenth.
How this dating was done: Radiocarbon dates charcoal and bone. Optically stimulated luminescence, a glow stored in quartz that resets when the grain last saw sun, dates sediment under the jars and so limits when they were set down. Uranium-lead ages in zircon crystals match a jar to a quarry. They do not date the carving.
What could change it: A sample from under a jar that has no burial cut through it, dated both ways, would pull the placement and the funeral into one sequence or keep them apart.

Published ranges, drawn as bars. A bar is a claim about a span, not a point.

Listing window

Sediment under jars at Site 2Contested

Human bone at Site 1

1240 BCE1 CE1219 CE

Listing window. UNESCO’s span, about 500 BCE to 500 CE, possibly to 800 CE. A cultural window, not one jar.
Sediment under jars at Site 2. Four ages in the top 10 centimetres under two jars, averaged to about 1240–660 BCE. A limit on placement at that spot.
Human bone at Site 1. Two published bone ranges, about 772–950 CE and 1046–1219 CE. Burials around jars, not the day a jar was carved.

What is actually there

More than 2,100 jars are known in Xieng Khouang, and 1,325 of them stand in the fifteen listed sites.
Jars reach about 3 metres in the listing’s general account, and about 2.5 metres at Site 1.
Stone discs are read as possible lids.
The quarry match is a crystal age, not a written label.

Open questions

Question	Status
Were the jars set in the late second millennium BCE, in the listing’s Iron Age, or more than once?	Open. The clocks do not yet agree.
Did a jar hold a body, or mark a place where bone was buried later in the ground?	Open. Both primary and secondary burials are published beside the jars. A jar used as a coffin is not what the recent digs found inside them.

The current narrative

Where publication stands today. It is the best-supported reading, and it is open to revision. It is not a verdict.

The current narrative — open to revision

Jars set first, graves added over a long time

The jars were carved and stood on the plain, possibly as early as the late second millennium BCE at Site 2, and people kept using the places for burial into the early second millennium CE. The Iron Age window is the listing’s summary of that funeral culture, not a single generation.

What supports this

The glow-dates under two jars at Site 2 cluster centuries before the bone at Site 1.
Primary burials, bundled bone, and bone in ceramic jars are all published at Site 1, so the rite itself was not one gesture.
A quarry of unfinished jars shows the carving happened on the mountain, not in a later village.

What pushes back

Charcoal under one Site 1 jar is medieval, and disturbance from a burial can put a late sample under an older stone.
One pair of jars is not every group on the plateau.

What would settle it

It is the centre because the two clocks are both published and they do not collapse. It moves if a clean sample under an undisturbed jar lands inside the listing’s window only.

Emerging narratives

Other published readings. Each may be right. None is adopted here unless the evidence carries it.

An emerging narrative

One Iron Age funeral, and the other dates are noise

The jars, the discs, and the burials belong to the culture the listing describes, between about 500 BCE and 500 CE, perhaps stretching toward 800 CE. Earlier glow-dates are the age of the soil, and later bone is a reuse too thin to rename the monument.

What supports this

The listing’s window is tied to the jars, the discs, and the goods, and it is the synthesis for the whole serial property.
A glow-date on wind-blown silt can be older than the jar if the jar did not turn the soil.

What pushes back

The Site 2 study argues the top ten centimetres were disturbed until the jars stopped that disturbance, which is why those ages are read as placement.
Bone dates in the eighth to thirteenth centuries CE are burials, not stray charcoal.

What would settle it

It keeps the listing’s window visible. It needs the later bone to be a different event from the jars, which the digs have not yet shown.

Should the current view be reevaluated?

Open to revision

The jars, the quarry, and the burials are solid. Which century the jars were stood in is not. Open keeps the listing’s Iron Age and the earlier placement date in the same room.

What drives this

More than 2,100 jars, with a matched quarry.
Glow-dates under Site 2 jars in the late second millennium and early first millennium BCE.
Bone dates centuries after the listing’s main window.

This is the museum’s own weighing of the evidence. It is not a visitor vote, and it is separate from the slider.

Weigh it yourself

Anonymous. Nothing here is stored except on this browser. Your lean does not change the assessment beside it.

Jars set first, graves added over a long time Unsure One Iron Age funeral, and the other dates are noise

If the contested reading is right

What would follow if a reading that is not the consensus turned out to be true, and what could settle it. This explains the stakes. It does not adopt the reading.

The jars are older than the Iron Age graves

The plain would be a monument that outlasted the people who cut it, reused by later burials. Guides would date the standing of the stone apart from the bone in the grass.

Why it is still worth a test

Samples from under jars that no grave has cut, at more than one site.

Sources

Megalithic Jar Sites in Xiengkhuang – Plain of Jars UNESCO World Heritage Centre
Dating the megalithic culture of Laos PLOS ONE, 2021
Mohs scale of mineral hardness Wikipedia

Image credits

Site 1 on the Plain of Jars. The nearest jar is hollowed out. The listing counts more than 2,100 jars of this kind across Xieng Khouang. . Jakub Hałun, CC BY-SA 4.0. Shown unedited.
The same group from a little farther off. Hills close the plateau. The jars are not in rows. . Jakub Hałun, CC BY-SA 4.0. Shown unedited.

← Laos World map