Compositional Changes in Glass Beads in the Sa Huynh–Champa Cultural Tradition: Evidence from Central Vietnam

TAMURA Tomomi1*, MIYAMA Emily2, OGA Katsuhiko3, and NGUYỄN Khánh Trung Kiên4

This study examines the chemical composition of glass beads excavated and collected from archaeological sites in central Vietnam in order to clarify changes in glass supply and exchange networks in Southeast Asia. The materials analysed include glass beads and related glass objects from several sites associated with the Sa Huynh cultural sphere and the early historic period, including Go Ma Voi, Go Dua, Go Cam, and Tra Kieu. Compositional analysis was conducted using XRF to identify major and minor elements and to classify glass types. The results revealed clear chronological changes in glass composition. At the Go Ma Voi site, most analysed samples are potash glass. Some beads and glass fragments show similarities to potash glass artifacts found at Ban Don Ta Phet in Thailand, suggesting connections with mainland Southeast Asian exchange networks. At the Go Dua site, potash glass remains dominant, particularly cobalt-blue potash glass associated with Indian production and copper-blue potash glass linked to regions from central Vietnam to southern China. At the Go Cam site, both potash glass and soda glass appeared, indicating a transitional phase in glass supply. In contrast, assemblages from Tra Kieu are dominated by high-alumina soda glass, a type widely distributed in Southeast Asia and also known from sites such as Oc Eo. These results suggest that central Vietnam was integrated into wide-ranging exchange networks linking South Asia, mainland Southeast Asia, and East Asia, and that changes in glass composition reflect broader shifts in regional trade and interaction.