Production Technology and Provenance of Dvāravatī Glass Beads from Khu Bua, Central Thailand: An Archaeometric Study

The production technology and provenance of 22 beads from the Dvāravatī-period site of Khok Phithak at Khu Bua, central Thailand (6th–11th centuries CE), was investigated using a multi-analytical approach combining VP-SEM-EDS, LA-ICP-MS, and micro-Raman spectroscopy. Macroscopic and microstructural evidence indicates that most of the glass beads were manufactured by the drawn-tube method, consistent with the supply of imported Indo-Pacific beads rather than local primary glass production at Khu Bua. However, the assemblage is not technologically homogeneous. From a compositional point of view, 19 beads belong to the m-Na-Al-1 subgroup, linking them to South Asian glassmaking traditions and the large-scale Indo-Pacific bead industry. One bead corresponds to plant-ash soda–lime glass, indicating an additional supply stream, while two outliers, a slag-derived ferruginous glass bead and a chalcedony/agate bead, demonstrate that bead circulation at Khu Bua also involved materials of distinct technological and geological origin. Coloring and opacification technologies, including Pb-Sn opacifiers in green and yellow-green beads and copper-based striking in orange beads, further indicate the use of technologically controlled recipes beyond simple bulk glass import. These results support the interpretation of Khu Bua as an inland consumer center embedded within long-distance Indian Ocean exchange networks.