The Australia National University and Lao Department of Heritage have confirmed that thousands of ancient stone jars scattered across Laos were used as communal burial vessels—solving a 90-year mystery and illuminating a previously unknown chapter of Southeast Asian mortuary practice. For the first time, archaeologists found intact human remains inside the jars themselves, offering direct evidence of their funerary purpose and revealing that the sites served as active burial grounds for generations of families over hundreds of years.
Why This Matters
• New evidence for history: At least 37 individuals discovered inside a single jar, dated between the 9th and 12th centuries C.E.
• Trade revelation: Glass beads from South India and Mesopotamia found in the jar, showing intercontinental trade routes reached remote highland Laos
• Regional heritage: The discovery reshapes understanding of Iron Age and medieval ritual practices in mainland Southeast Asia
• Tourism context: The Plain of Jars is a UNESCO World Heritage site, increasingly accessible to visitors from Thailand and beyond
Breakthrough at Site 75
Led by Nicholas Skopal of James Cook University and Souliya Bounxayhip from the Lao Department of Heritage, researchers excavated an exceptionally large jar at Site 75, located roughly 70 kilometers northeast of Phonsavan in the highlands of north-central Laos. Inside, they uncovered bones and teeth from no fewer than 37 individuals, including both adults and children. Radiocarbon dating of dental fragments traced these deposits to a 300-year span from approximately 890 C.E. to 1160 C.E.—well into the medieval period, centuries later than the Iron Age origins of the jars themselves.
The skeletal remains were arranged methodically: skulls lined the jar's rim, while limbs and other bones were grouped together in the center. This pattern suggests a deliberate, multi-stage burial rite. Researchers believe bodies were initially left to decompose in smaller stone containers or exposed locations, after which cleaned bones were collected and transferred into larger communal jars for permanent interment. The practice appears to have been maintained across several generations, likely by extended family groups or village communities.
The findings, published in the journal Antiquity, represent the most definitive proof to date that the Plain of Jars functioned as a vast burial complex. While earlier excavations—dating back to French archaeologist Madeleine Colani's work in the 1930s—had recovered burnt teeth and bone fragments around the jars, undisturbed burials within the vessels had remained elusive until now.
Artifacts Point to Distant Trade
Alongside the human remains, the excavation yielded a remarkable assemblage of grave goods. Among them: an iron knife, a small copper-based bell, earthenware fragments, five stone slabs, and 20 glass beads. Chemical analysis of the glass beads revealed compositions consistent with production centers in South India and Mesopotamia—regions thousands of kilometers distant from the landlocked highlands of Laos.
This discovery fundamentally revises the narrative of ancient Laotian communities. Far from isolated, the inhabitants of the Plain of Jars were participants in expansive trade networks linking mainland Southeast Asia with South Asia and the Near East. The beads likely traveled overland through what is now Thailand, Myanmar, and Yunnan, or via riverine and maritime routes connecting the Mekong basin to Indian Ocean commerce.
What This Means for Residents
For those living in Thailand, particularly in the northeastern provinces bordering Laos, the Plain of Jars is both a cultural neighbor and an increasingly popular cross-border heritage destination. The site was inscribed as a UNESCO World Heritage property in 2019, and Thai tourists—drawn by proximity and shared Tai-Lao cultural roots—make up a significant portion of visitors to Phonsavan.
The new findings add depth to that experience. Rather than viewing the jars as mere curiosities, travelers now understand them as sacred vessels marking multigenerational burial grounds. The trade links evidenced by Indian and Mesopotamian glass also underscore the historical interconnectedness of the region—reminding modern visitors that ancient highland communities in Laos were linked by commerce and culture to the very routes that once passed through what is now Thailand's northern corridor.
For academic and cultural institutions in Thailand, the research offers a comparative framework. Iron Age and medieval burial practices in Laos share parallels with traditions documented in northeastern Thailand and elsewhere in the Khorat Plateau. The discovery may prompt renewed interest in Thailand's own megalithic sites and burial archaeology.
Unanswered Questions Remain
Despite the breakthrough, key mysteries persist. Researchers still do not know which specific culture or polity carved the jars, nor how communities transported stones—some sourced from quarries 100 kilometers away—across rugged terrain. The jars themselves range widely in size, from small vessels under a meter tall to behemoths exceeding 3 meters in height and weighing several tons.
Optically stimulated luminescence (OSL) dating of sediments beneath the jars suggests they were first positioned as early as 1240 B.C.E. to 660 B.C.E., placing their origins squarely in the late Bronze Age or early Iron Age. Yet the human remains found in Jar 1 at Site 75 date to the 9th through 12th centuries C.E.—implying that the jars were carved and placed many centuries before they were repurposed or continued in use as burial vessels.
Why jar-making ceased around 500 C.E. is another enigma. Some scholars speculate that political upheaval, migration, or shifts in religious practice ended the tradition. Others propose that the communities simply evolved different funerary customs. DNA testing of the recently recovered remains is now underway, which may reveal kinship patterns, diet, health, and ancestry—potentially linking the buried individuals to modern ethnic groups in the region.
Local Folklore and Modern Science
Lao folklore has long attributed the jars to a legendary giant king named Khun Cheung, who purportedly ordered their creation to brew vast quantities of rice wine in celebration of a military victory. While charming, this origin story is now understood as a cultural narrative rather than historical fact. The romantic notion of celebratory brewing has given way to a far more solemn reality: the jars were monuments to the dead, sacred repositories for ancestors over many human lifetimes.
The Plain of Jars comprises more than 90 known sites with an estimated 2,100 individual stone vessels, spread across the highland valleys of Xieng Khouang Province. Many areas remain contaminated with unexploded ordnance from decades of conflict, limiting both excavation and tourism. Gradual clearance efforts have opened additional sites in recent years, though safety concerns persist.
Broader Implications for Southeast Asian Archaeology
The research team's findings challenge earlier assumptions that the jars belonged solely to the Iron Age. The confirmed use of the jars during the 9th to 12th centuries positions them within a medieval context, contemporaneous with the rise of early states and complex societies elsewhere in mainland Southeast Asia—including the Khmer Empire and Pagan Kingdom.
The presence of South Indian and Mesopotamian glass further situates the Plain of Jars within the broader narrative of Eurasian connectivity during the first and second millennia C.E. These highland communities, often presumed peripheral, were in fact nodes in transcontinental exchange systems that moved not only trade goods but also ideas, technologies, and ritual practices.
Future excavations, planned for additional jar sites, aim to test whether the burial practices documented at Site 75 were universal or whether different regions and time periods followed distinct rituals. The diversity of jar sizes, locations, and associated artifacts suggests considerable variation across the landscape.
For now, the mystery is not fully "solved"—but it has been profoundly clarified. The Plain of Jars stands as a testament to the endurance of ritual, the reach of ancient commerce, and the capacity of archaeology to recover voices from a distant, unwritten past.
