Glass beads from Guishan in Iron Age Taiwan: inter-regional bead exchange between Taiwan, Southeast Asia and beyond

Archaeological excavations at Guishan in the southern end of Taiwan have recovered more than a hundred glass beads dating to mid-1st millennium AD. This research investigates the exchange of glass beads between Guishan, eastern Taiwan and Southeast Asia, by analysing the styles, chemical composition and microstructure of 64 glass beads, using SEM-EDS, EPMA and LA-ICP-MS. The findings suggest that beads with an m-Na-Al glass and v-Na-Ca composition are most common, supporting evidence for bead exchange between Guishan and Southeast Asia. Furthermore, most m-Na-Al glasses were coloured by copper, and different types of copper-based additives may have been used for different colours, indicating the beads may be derived from multiple production centres or workshops via Southeast Asia. Conversely, the glass bead compositions suggest that glass bead exchange between other contemporary sites in Taiwan is less evident at Guishan, except for one type of yellow glass bead containing bone ash which is different. This bone-ash containing yellow glass at Guishan is firstly identified in Iron Age Taiwan as well as around the South China Sea region. Its counterparts are also found from archaeological sites in southeastern and coastal eastern Taiwan, which might indicate small scale glass bead exchange. This evidence together suggests a dynamic glass bead exchange network between Guishan, eastern Taiwan, Southeast Asia and beyond.