Glass bangles from the Yemeni workshop of Kawd am-Saila, Aden (c.14th–16th century): Defining a high-alumina plant-ash (v-Na-al) group

This paper presents compositional results and typological distinctions for glass bangle debris collected from the Yemeni workshop of Kawd am-Saila (c. 14th–16th centuries) in the province of Aden, and small contemporary collections from nearby al-Karf Road and neighbouring Somaliland held in the British Museum. These bangle fragments share the same typological designs and colour repertoires, consistent with export from Yemen to the Horn of Africa. Archaeochemical analyses were undertaken using SEM-EDX at the British Museum and LA-ICP-MS at CNRS Orléans and the UCL Institute of Archaeology. This study applies an established geochemical framework to identify a new, internally coherent category of glass termed ‘KAS’, characterised by distinct silica and plant-ash sources most likely associated with the region of Aden, consistent with archaeological indications of secondary production at the Kawd am-Saila workshop. The comparative collections were also found to be primarily of this previously undocumented ‘KAS’ composition and the few fragments with typological differences corresponded to other established regional glass groupings.

KAS is a soda-lime-silica plant-ash glass most notable for elevated alumina concentrations (c. >4 wt% Al2O3), placing it within the so-called ‘v-Na-Al’ compositional category, a characteristic often associated with Central Asian glass (c. 9th–17th centuries). This study defines the key compositional characteristics of KAS, establishing a new categorisation for a potential South Arabian glass production zone by highlighting notable differences from contemporary Central Asian glasses. Identification of this proposed new composition contributes to a better understanding of plant-ash glasses, offering a new regional reference point for Islamic glass studies. The findings also provide insights into production techniques, compositional variability and circulation patterns of glass bangles across the western Indian Ocean during the medieval to early modern period.