Unguja Ukuu, Zanzibar: Geochemical and Biomolecular Analyses of East Africa's Early Indian Ocean Trade
Biological and cultural diversity around the Indian Ocean have been shaped by a long history of maritime trade. These cross-cultural exchanges saw the long-distance movement of people, goods, and various plants and animals to new and often far-flung regions stretching between eastern Africa and China. The nature of eastern Africa’s role in early long-distance trade, especially the timing and influence of Asian connections, remains ambiguous. A major limitation in this regard has been the limited application of archaeological science methods at Iron Age sites in this region, which often lack precise chronologies constructed through scientific dating methods. Material goods such as beads, metal and ceramics have typically been traced to their presumed point of origin through stylistic, rather than geochemical, means, while reports of early exotic plant and animal introductions have not been accompanied by robust taxonomic identifications and direct dating. In this seminar, I present the results of new geochemical and biological evidence produced by the Sealinks Project though renewed archaeological investigations site of Unguja Ukuu on Zanzibar. Dating between c. 650–1000 CE and covering some 17 hectares at the height of its occupation, Unguja Ukuu is one of the earliest known trading ports on the eastern African coast south of Somalia and was thus a critical port of call for trade goods entering and leaving the region. Building on a previous research at the site that began during the 1960s, we returned in 2011 and 2012 to recover new higher-resolution cultural sequences for chronological, geochemical and bimolecular analyses so as to provide further insights into the origins of the goods and species that reached Zanzibar in his time period. These studies included systematic analyses of plant and animal remains, including the application of ancient DNA and collagen fingerprinting (ZooMS) to enable more secure identifications of introduced species such as black rat and chicken; LA-ICP-MS analysis of imported trade goods to provide more robust assessments of provenience and the web of connections that led to their deposition on the African coast; and the construction of a Bayesian-informed chronology for the site based on a new suite of 31 AMS radiocarbon, to provide firmer dates for the introduction of key trade wares. Many of these methods have seldom if ever been applied to Indian Ocean trading sites, particularly of the late Antique and Medieval time frame, and we examine not only the ways they inform about eastern Africa’s entry into the world of Indian Ocean exchange and commerce, but also the broader insights they provide into an increasingly expansive and complex set of Old World trading networks.
About the Presenter
Alison Crowther is a Postdoctoral Research Fellow in the School of Social Science, UQ. She completed her PhD at UQ in 2009, which examined early plant agriculture in the Pacific through starch residues on Lapita pottery. After this, she lived in the UK for six years, where she was a Marie Curie Research Fellow in Archaeobotany at the University of Sheffield (2008–2009), then a British Academy Postdoctoral Research Fellow (2010–2013) and St Cross College Junior Research Fellow (2011–2013) at the University of Oxford. She returned to Australia in 2014 and lectured at the UQ for a year before taking up her current post. Alison has been working in eastern Africa since 2010 as part of the ERC-funded Sealinks Project, investigating the origins and development of Indian Ocean trade and interaction. Her fieldwork in this region has covered a vast expanse of the Swahili coast and islands, including the mainland coasts of Kenya and Tanzania, and the islands of Pemba, Zanzibar, Mafia and Madagascar. Her interests include the archaeobotany of early agriculture in East Africa, Indian Ocean trade and crop transfers, and residue analysis of ancient food processing technologies.