The trade of glass beads in early medieval Illyricum: towards an Islamic monopoly

The trade of glass beads has long been assumed to have been under Islamic dominance during the early centuries following the Arab conquest of the Middle East, judged by the prevalence of Islamic beads in the archaeological contexts from Viking Scandinavia to medieval Morocco. This paper explores the impact of the Byzantine-Slavic transition on the use and by extension trade of glass beads in the Balkans from the seventh to the ninth century CE. A series of 48 glass beads and 4 vessel fragments from two excavated sites in modern day Albania have been analysed morphologically, technologically and chemically by LA-ICP-MS. The seventh-century beads from Lezha have typological parallels among central European assemblages and are made from recycled natron-type glass. The presence of a high lead-iron-natron variant is of particular interest as it potentially reflects a regional production. The ninth-century beads from Komani are made from soda-rich plant ash glass from the eastern Mediterranean and Mesopotamia and correspond to an Islamic typology. The chronological and geographical differences are reflected in the distinctive cobalt sources used for the two groups. While the beads from Lezha are coloured with a cobalt not correlated with any particular element, the cobalt source of the Komani samples is associated with zinc, typical of Islamic glass making. It thus appears that the supply of beads during the seventh century when the Balkans were under Slavic occupation relied on regional production and recycled material, and that a long-distance trade with the eastern Mediterranean was revived following the Byzantine re-conquest of the south-eastern Adriatic in the ninth century. Intriguingly, the Albanian finds confirm the Islamic control of the production and trade of glass beads during this period and highlight the mediatory role of the Byzantine Empire. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12520-017-0583-5) contains supplementary material, which is available to authorized users.