The "Macro-Sudan belt": Towards identifying a linguistic area in northern Sub-Saharan Africa

sense a robust geographical commonality. The northern and southern boundaries of the Macro-Sudan belt apply to the different features regularly and thus seem to be more or less stable; movements across them appear to be associated with a change in profile on the part of the linguistic population (cf. the cases of Chadic and Bantu with regard to the presence or absence of features). As opposed to this, the eastern and western extensions of the individual isoglosses are subject to considerable variation. This suggests that the linguistic features seem to have predominantly undergone historical expansion in an eastward and/or westward direction. That is, the overall historical dynamic within the area has an east-west rather than a north-south trajectory. Moreover, the existence of a particularly homogeneous nucleus, the hotbed, can be interpreted as a possible innovation area that has repeatedly, and to varying degrees, radiated into the periphery along this horizontal axis. In Section 1 I have given a rough outline of the Macro-Sudan belt. In so doing, I have referred to non-linguistic, geographical concepts: the Sahara~Sahel marking the northern boundary and the Atlantic Ocean and the Congo Basin the southern boundary. Since the distribution of linguistic features can be correlated with these geographical entities, I venture the hypothesis that the Macro-Sudan belt is primarily the result of geographical factors which have obtained for a sufficiently long time period. This means that it was not the mere presence or absence of contact between different linguistic populations that shaped the Macro-Sudan; in principle, conditions for contact situations of any kind (due to exchange between sedentary groups, group migration, long-range feature diffusion, etc.) can be assumed to exist almost everywhere. The crucial point is that relatively stable geographical macro-areas differ according to their conditions for human subsistence: heterogeneity between vs. homogeneity within areas. Thus, the impact of population contact across major geographical boundaries tends, over a long time span, to be lower than is the case with contacts not involving such boundaries. With respect to the Macro-Sudan, its northern and southern limits were, relatively speaking, a greater barrier for population exchange/movement or the flow of individual features associated with populations; by contrast, these processes tended to be facilitated along the west-east trajectory. In other words, stable geographical factors have been constantly reinforcing migration and contact patterns in this part of Africa