African Archaeological Review

, Volume 32, Issue 3, pp 443–463 | Cite as

Potsherds Coated with Lime Mortar Along the East African Coast: Their Origin and Significance

  • Elgidius B. IchumbakiEmail author
  • Edward Pollard
Original Article


This paper investigates the purpose of lime mortar-coated potsherds found along the East African coast. Recent sites investigated are in areas of Kaole, Kiswere, Rushungi, Sudi, and Mikindani in Tanzania. Desktop research revealed similar potsherds from Manda in the Lamu Archipelago of Kenya and Kilwa Kisiwani in Tanzania. From the late first millennium AD, asphalt has been recorded on pottery at Manda to make it waterproof. From around the same period, mortar was found on pottery at Kaole and on other artefacts in the midden deposit such as ‘bead’ grinders and bone deposits. This suggests natural cementation from lime introduced to the midden deposit. A thin layer of plaster on pots dating to the late twelfth to late thirteenth centuries at Kilwa Kisiwani, and eleventh to fourteenth centuries at Sudi, has been interpreted as deliberate to make the vessel more watertight. Later evidence indicates that the tradition of coating pots with lime mortar probably for the purposes of storing liquids continued up to the seventeenth and eighteenth centuries at Mikindani. However, vessels and deposits dating from the late twelfth and thirteenth centuries at Kiswere and Bwembweni, near Kaole, contain layers of mortar too thick for the purpose of waterproofing the vessel, and were probably used for mixing and then coating a building. The coastal and estuarine settings of the find spots indicate the importance of water transport for this lime mortar industry. The storage and transport of lime along the coast and inland would have been a significant part of local East African trade for its use in iron making and building.


East African coast Lime mortar Pottery Kaole Kiswere Mikindani Sudi 


Cet article étudie la poterie couvri chez mortier trouvé sur la côte de l'est del'Afrique. Les sites étudiés pendant enquête sur le terrain sont Kaole, Kiswere, Rushungi,Sudi et Mikindani en Tanzanie. La recherche a révélé la poterie similaire à Manda, dansl'archipel de Lamu du Kenya, et Kilwa Kisiwani en Tanzanie. De la fin du premier millénairede notre ère l'asphalte a été enregistrée sur la poterie à Manda pour la rendre étanche.D'autour de la même période le mortier a été trouvé sur la poterie au Kaole et sur desautres objets dans les fouilles comme les perles et les os. Cela suggère la cimentationnaturelle de la chaux introduite au dépôt. Une couche de mortier sur la poterie datant de lafin du 12ème à la fin du 13ème siècle à Kilwa Kisiwani et 11ème au 14ème siècle au Sudi aété interprète comme délibéré afin de faire la poterie plus étanche. La preuve indique quela tradition de la poterie chez une couche de mortier a continue jusqu'aux 17ème et 18èmesiècles à Mikindani probablement pour la conservation des liquides. Toutefois, la poteriedatant de la fin du 12ème au 13ème siècle au Kiswere et Bwembweni, près de Kaole,contient des couches de mortier, trop épaisses pour le but de faire imperméable la poterie.Donc, la poterie est pour mélanger le mortier, et est probablement pour la construction. Lessites côtiers et estuariens indiquent l'importance du transport de l'eau pour cette industriemortier. Le stockage et le transport de la chaux le long de la côte et l'intérieur auriaent étéune partie importante du commerce africain est pour sa utilisation dans les travaux de fer et de construction.



Thanks are due to Prof. Bertram Mapunda from the University of Dar es Salaam and Dr. Colin Breen from the University of Ulster for supporting the research. Edward Pollard’s 2012 research was funded by a British Academy small grant, and a vehicle and excavation equipment from the British Institute in Eastern Africa were used. E. Ichumbaki’s research was funded by the University of Dar es Salaam. Students from the University of Dar es Salaam assisted in surveys and excavations. The Department of Antiquities, Ministry of Natural Resources and Tourism is thanked for issuing several permits for several periods of research and whose results are reported in the paper. The authors would like to thank the editor and anonymous reviewers for their helpful comments.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Department of Archaeology and HeritageUniversity of Dar es SalaamDar es SalaamTanzania
  2. 2.British Institute in Eastern AfricaKileleshwaKenya

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