In 1950, Peter Williams-Hunt published a paper in Antiquity entitled ‘Irregular earthworks in eastern Siam: a review’. A former RAF pilot, he had pored over wartime aerial photos taken of the extensive Khorat Plateau in North-east Thailand. He was intrigued by the numerous enigmatic prehistoric sites, at first sight reminiscent of moats around a medieval castle, which are in fact occupation mounds surrounded by up to five concentric banks. Twenty years after his article was published, I found myself excavating within one of these sites, large enough to contain several modern villages, which lay alongside a salt pan. When we arrived to start excavations, it was the scene of intensive dry-season salt production. I have since excavated another four of these moated sites, and we confirmed Williams-Hunt’s conclusion that: ‘Further comment would be futile. The excavator’s spade alone will provide the final answer.’
Over the years, we have achieved several breakthroughs, all of which have only been made possible by collaborating with a large team of specialist colleagues. The most compelling question, was the purpose of the moats, some up to 40m wide. Long posited, this issue was resolved in a matter of days when we decided that the only way forward was to excavate right across them, beginning at the site of Noen U-Loke. We took the bull by the horns and hired a powerful digger that, within a day, had opened a trench several metres deep and nearly 200m in length. Bill Boyd, our geomorphologist, then mapped the stratigraphy before water rose up and filled the trench, finding that the moats were flat-based, with no hint of a defensive purpose. The banks had been built up by accumulating the surface soil in order to retain water fed from a nearby stream. This procedure was replicated at four other sites with the same results, and radiocarbon dating placed their construction in the later Iron Age, between 100 BC and AD 400.
Other insights followed: they were built over when the monsoon rains faltered, heralding centuries of relative aridity. Then blacksmiths began forging iron ploughshares and sickles, and the inhabitants, men and women, were interred in their own houses, some with remarkable wealth expressed in gold and silver, carnelian and agate, and quantities of bronze ornaments. Significantly, rice was now grown in permanent wet fields rather than dryland plots fed only by rainfall, and we concluded that the moats fed irrigation water into the new fields, ensuring a bountiful and predictable harvest. We found a house that had been burnt to the ground, leaving carbonised rice grains all over the kitchen floor, and now the dead were interred in graves filled with rice.
