ABSTRACT
The core of the northern half of west Africa was a broad open savannah, gradually giving way to the scrubby semi-arid lands of the Sahel as one moved north, until eventually one came to the vast expanse of the Sahara desert. The savannah region and part of the Sahel were penetrated by two great rivers-the Senegal on the west and the looping Niger on the east, as well as a host of shorter rivers that all emerged from the highlands of Futa Jallon in the south and found their way to the sea. The rivers brought water to the tricky and variable climates of the Sahel and the bend of the Niger passed through land that might otherwise have been desert. Even further south, where rainfall was adequate for full time agriculture, the rivers and streams provided a vast transportation network that not only allowed irrigation but permitted the concentration of agricultural resources over larger areas and underwrote chains of towns and, on the Niger, thriving significant cities. As one neared the coast, especially the coast around the Gambia and south of it, the network of rivers thickened and combined with forests to became a complex riverine environment of creeks, estuaries and small rivers, promoting a unique flora of a semi-flooded environment. This environmental break also provided a significant break in the nature of warfare and separates the Guinea coast south of the Gambia from the great savannah and desert to its north and east.
