Geophysical Survey in Sub-Saharan Africa: magnetic and Electromagnetic Investigation of the UNESCO World Heritage Site of Songo Mnara, Tanzania

Magnetometry and Slingram electromagnetic surveys were conducted at the UNESCO World Heritage Site of Songo Mnara, Tanzania, as part of a multi-national programme of investigation to examine the uses of space within and outside of this stonetown. The town was a major Islamic trading port during the 14th and 15th centuries.The surveys detected significant evidence for the containment of activities within the town walls, and previously unknown anthropogenic activity was revealed between the existing coral rag buildings, as well as within the open areas inside the town. Over 40 areas of magnetic disturbance were identified that corresponded directly with areas of high magnetic susceptibility in the Slingram electromagnetic in-phase responses.On excavation many of these anomalies were found to correlate with wattle and daub structures, indicating a hitherto unidentified population, and the location of the anomalies also suggests a potentially deliberate delineation of space within the open areas of the stonetown. The combined results of the three geophysical data sets indicate that there are clear delineations in the use of space within Songo Mnara. This coupled with the presence of industrial activities and evidence of more ephemeral occupation, neither of which had previously been recorded at the site, indicates that the pre-existing town plan is in need of significant reappraisal. The current plan, based upon the remains of extant and collapsed coral buildings, can now be updated to incorporate the more ephemeral aspects of Swahili sites including activity areas, and notably, the homes of the ‘hidden majority’of the population.The results establish the benefit of a combined approach at these sites, and demonstrate that further invasive and non-invasive exploration is required in order to fully exploit the significance of the role of geophysical techniques in understanding Swahili towns

A GIS Approach to Finding the Metropolis of Rhapta

The Periplus of the Erythrean Sea is a description of trade networks in the western Indian Ocean written as a guide for merchants (Casson 1989: 5). This text provides a description, varying in detail, of a multitude of regions, including the geographic features, settlements, ports, and peoples to be found in each. The original text, dating to approximately 30–40 CE, no longer survives, but a copy, believed to date to the tenth century, has been preserved and is currently housed in Heidelberg (Graf 1994: 143). The southernmost location mentioned in the text is the port of Rhapta, on the East African coast. This port is also mentioned in Ptolemy’s Geography, a second-century CE geographical account, in which it is termed a mētropolis and located “a short distance from the sea” (mikron apothen thalassēs), that is, the mouth of the Rhaptos river which flowed into the Indian Ocean (4.7.12). The exact location of Rhapta has been the subject of a lengthy historical debate owing to a lack in the text of any description of recognizable geographic features associated with, and the absence of any notable archaeological sites that can unequivocally be attributed to, the port (Hoyle 1967: 95; Horton 1990: 97; Kirwan 1986: 99)

Pillar Tombs and the City : Creating a Sense of Shared Identity in Swahili Urban Space

This paper reviews published research on Swahili pillar tombs, as a specific type of tombs built of stone, by summarising records on almost fifty sites on the east coast of Africa. Dated to the 13th–16th centuries AD, the pillar tombs represented a core component of Swahili urban space. By considering their spatial setting, characteristics and comparative case studies from Africa and the Indian Ocean world, the paper reconsiders how pillar tombs might have functioned as a type of material infrastructure for creating social ties and notions of shared identity in a society that has never formally united