Import globally, recycle locally: Provenance of the Middle Byzantine Morava and Braničevo glass bracelets, using Sr and Nd isotopes and trace elements

Sr and Nd isotope and trace element analyses were conducted to determine the provenance of Middle Byzantine Morava and Braničevo glasses. Analyses reveal four distinct glass groups. Group BM1 consists of Late Antique natron glass from Levantine and Egyptian sources, while BM2 includes Islamic plant ash glass likely from Beirut, Damascus, and Raqqa. Group BM5 features a soda-lime flux rich in borates, probably from Bigadiç deposits in western Anatolia. Its highly mature, mineral-depleted sand matches Anatolian geology, though some similarities with Ctesiphon glass suggest possible recycling with Mesopotamian glasses. Despite this, the Anatolian origin of BM5 remains most likely. Groups BM3 and BM4 represent recycled mixtures of BM1, BM2, and BM5. Strong trace-element and isotopic correlations, together with a furnace fragment and local metallurgical contamination, indicate local bracelet production at Braničevo and Morava. These results support an emerging picture of a Byzantine glass industry that relied on both Anatolian raw materials and imported glass from the Islamic Levant and beyond. The paper presents the first-ever isotopic data for high-boron Byzantine glass.