explicit sampling strategies, and establishment of basic time-space systematics. The explanatory framework emphasizes processes of endogenous change instead of diffusion and migration. This approach has been applied at several locales along the middle Niger in Soninke-speaking zones that are linked in oral traditions to the Ghana kingdom as well as along the MSV in the general area thought to correspond to the Takrur polity. This work has revealed some basic aspects of the development of society and economy in the first millennium a.d. at a time prior to, and overlapping with, the emergence of historically documented regional polities in the eighth or ninth (Ghana) and eleventh (Takrur) centuries.

Southeast of Koumbi Saleh, in the Mema and adjacent inland Niger delta, research has demonstrated that settlements in favorable areas grew rapidly in the middle part of the first millennium under improved hydrologic and climatic conditions. Occupation mounds such as Toladié in the Mema reached eighty hectares before being abandoned, apparently owing to increasing dryness in the twelfth or thirteenth century (Togola 1996). The growth of occupation mounds has also been documented further east at Tango Maare Jaabel. Jenné-jeno in the inland delta achieved its maximum size of thirty-three hectares before a.d. 900 after being founded ca. 200 b.c. Jenné-jeno’s expansion was linked to the development throughout the first millennium of local trade networks in iron, stone, and staple commodities along the Niger River and adjacent regions (McIntosh and McIntosh 1993). This research, plus Norwegian work on the first-millennium iron-smelting industry in the Mema (Håland 1980), and Dutch research on other sites in the upper inland Niger delta or Inland Niger Delta (IND) (Bedaux et al. 1978; van der Waals, Schmidt, and Dembelé 1993), has reoriented interest toward understanding the nature of indigenous societies in the western Sudan, their development through time, and the changes they sustained subsequent to the establishment of the trans-Saharan trade. French and Malian archaeologists have produced important work in this perspective on the occupation mounds of the lakes region in the lower inland Niger delta (Raimbault and Sanogo 1991), and there has also been an attempt to establish an integrated culture historical framework for the entire middle Niger south of Timbuktu in the first and second millennia a.d. (McIntosh, S. K., 1995, 360–372).

Along the central sector of the MSV, a research program very similar to the IND project was conducted by American and Senegalese researchers in 1990–1993 with the goal of recovering broadly comparable data sets on the organization and economy of societies in the two great floodplains of the western Sudan (McIntosh, McIntosh, and Bocoum 1992). In the MSV, the trajectory during the first millennium differed significantly from the rapid growth of occupation mound clusters encountered in the IND. In the former, sites appear to have remained small, undifferentiated, and homogeneous throughout the first millennium, experiencing rapid growth and change only after the appearance of artifacts related to the trans-Saharan trade in the ninth or tenth century a.d. The earliest brass and glass imports at the sites of Cubalel, Ogo, and Sincu Bara are associated with pottery imitating decorative motifs popular at Tegdaoust. Earlier reconstructions, in which sophisticated brass metallurgy and hierarchical political organization were thought to be present in the MSV from the fifth century a.d. (Thilmans and Ravisé 1980), are now known to be erroneous, the result of mixed and disturbed deposits (McIntosh and Bocoum 2000). It now appears likely that societies along the middle Senegal experienced major and extremely rapid transformation in scale and complexity in the tenth century. Historical evidence for the existence of towns and regional polities on the middle Senegal in the mid-eleventh century is provided by al-Bakri, who described the town of Takrur as well as the kingdom of Sila. One hundred years later, the historian al-Idrisi included Sila among the domains of the powerful Takrur king who traded gold and slaves with the north. New radiocarbon dates on over a dozen of the more than 40,000 iron-smelting furnaces documented at sites on both sides of the middle Senegal cluster in the early second millennium, which suggests that iron production