the end of the 12th century, Ghana no longer dominated the gold trade. The Soninke farmers and traders then settled further south and west in the early 13th century. Archaeological site The extensive ruins at Koumbi Saleh were first reported by Albert Bonnel de Mézières in 1914. The site lies in the Sahel region of southern Mauritania, 30 km north of the Malian border, 57 km south-southeast of Timbédra and 98 km northwest of the town of Nara in Mali. The vegetation is low grass with thorny scrub and the occasional acacia tree. In the wet season (July–September) the limited rain fills a number of depressions, but for the rest of the year there is no rain and no surface water. Beginning with Bonnel de Mézières in 1914, the site has been excavated by successive teams of French archaeologists. Paul Thomassey and Raymond Mauny excavated between 1949 and 1951, Serge Robert during 1975-76 and Sophie Berthier during 1980–81. The main section of the town lay on a small hill that nowadays rises to about 15 m above the surrounding plain. The hill would have originally been lower as part of the present height is a result of the accumulated ruins. The houses were constructed from local stone (schist) using banco rather than mortar. From the quantity of debris it is likely that some of the buildings had more than one storey. The rooms were quite narrow, probably due to the absence of large trees to provide long rafters to support the ceilings. The houses were densely packed together and separated by narrow streets. In contrast a wide avenue, up to 12 m in width, ran in an east–west direction across the town. At the western end lay an open site that was probably used as a marketplace. The main mosque was centrally placed on the avenue. It measured approximately 46 m east to west and 23 m north to south. The western end was probably open to the sky. The mihrab faced due east. The upper section of the town covered an area of 700 m by 700 m. To the southwest lay a lower area (500 m by 700 m) that would have been occupied by less permanent structures and the occasional stone building. There were two large cemeteries outside the town suggesting that the site was occupied over an extended period. Radiocarbon dating of charcoal fragments from a