Wire wound trade beads dating
Most are ruby-red, but a few amber colored and one emerald green specimen have been recovered.
Thirty-three were found at Kilwa; all other sites combined account for another 16.
Studies of trade in the Indian Ocean between the 7th and 17th centuries have paid relatively little attention to the far western edge of that great sea.
Yet the eastern African coast1 was an active and important participant in that trade, supplying raw materials that were sought after and traded as far away as China.
Wound beads are made by winding molten glass onto a mandrel (usually an iron rod or wire) until the desired bead volume is reached.
While still viscid, the beads can be shaped by marvering or manipulating with various tools; they can also be decorated with glass of different colors.2 Apart from a few beads made of lead-silica glass (discussed below), all those found in eastern and southern Africa are made of soda-lime-silica glasses.
Such glasses are made by melting either sand or crushed quartz.
The past few decades have seen technological advances that have encouraged a surge in glass studies aimed largely at sourcing the origins of the raw glass.
This raw glass, as well as recycled scrap glass, was widely traded, so beads were often made at venues different from the glass itself, sometimes even on different continents.
Thus, the methods by which the beads were made also need to be taken into account in attempting to determine their region of production.
Based on the chemical composition of the glass and method of manufacture, these beads would have been made in China.4 They all come from sites that encompass the early 15th century, the period in which the fleets under the command of the Chinese admiral, Zheng He, are believed to have visited Africa’s East Coast (1417–14–1422)5.
Although it is possible these beads reached East Africa indirectly, comingled with other trade goods from China such as ceramics, this seems unlikely given the very limited numbers that have been found in East Africa and the circumscribed time span in which they appear.
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The Chibuene series is characterized by small (2.5–3.5 mm diameter) drawn beads with slightly rounded ends.