The highlands of Northwestern Thailand are scattered with dozens of caves that house some extremely curious human burials from the ancient past. They consist of large wooden coffins – often several meters long and crafted from a single tree trunk – that are mounted above the floor on wooden stilts.
The 40 or so burial sites are the work of a mysterious Iron Age culture that inhabited the Mae Hong Son province in northern Thailand between 2,300 and 1,000 years ago.
In a new study, archeologists carried out a genetic profile of 33 ancient people buried at five Log Coffin culture sites and traced back their ancestries, illuminating the complex genetic landscape of mainland South East Asia after the Stone Age.
Previous studies based on single individuals or single sites indicated that this culture were related to farmers from the Yangtze River valley in southern China and the local Hòabìnhian hunter-gather societies.
This latest study by the Max Planck Institute for Evolutionary Anthropology provides a deep insight into that relationship by looking at dozens of individuals from numerous sites. Their analysis suggests that, in fact, the farmer side of their genome can be divided further into two groups: one connected to the Yangtze River Valley and another to the Yellow River Valley in China.
“Our results contribute to the emerging picture of a complex genetic landscape in post-Neolithic mainland Southeast Asia; however, this study provides successful genetic results from samples in limestone caves from the northwestern highlands of Thailand. Future studies of samples retrieved from open-air archaeological sites in the lowlands seem promising. If possible, they can provide additional insight into the genetic history of Mainland Southeast Asia,” Wibhu Kutanan, study author and biologist from Naresuan University in Thailand, said in a statement.
Culturally speaking, it’s hard to know the precise significance of ancient Thailand's super-long log coffins. Why did an Iron Age culture go to such great lengths to raise the long trucks onto stilts? Was it a practical concern or did it hold some spiritual value?
The new study doesn’t delve too deeply into these questions, it simply notes: “Coffins were cut from a single tree and feature distinct carvings at the head and foot ends, which may reflect societal beliefs, the status of the deceased, the skill of the coffin’s maker, or indicate family or clan cemeteries.”
However, it is evident that other ancient cultures from mainland Southeast Asia have similar traditions. Over 170 boat-shaped coffins have been recovered from 44 different archaeological sites in nearby Vietnam, which are widely attributed to the Dong Son culture that lived in the region from 1000 BCE until the first century CE.
The cultural relics from Vietnam are typically put in the same bag as Europe’s boat burials in which the deceased, usually those who have a high social status or warrior credentials, are laid to rest in the hull of a ship as if the dead are being sent on a voyage towards the afterlife.
As shown by the new study, there was a vast amount of migration and intermingling in southeast Asia over 2,000 years ago. Given this interconnectivity, it's no surprise that it wasn’t just genetic information that was passed on, but also cultural information.
The study is published in the journal Nature Communications.