ABSTRACT
Geological changes in eastern Africa during the Miocene epoch, about fifteen million years ago, had the effect of preparing the region for human society. Huge tectonic upheavals raised a forested upland by about 900 meters and created the highlands of contemporary Ethiopia, Kenya, and mainland Tanzania. Areas lying between the walls of the eastern and western Rift were cast under permanent rain shadows, depriving the tropical forests of essential moisture and providing conditions favorable to the savanna of grass and scattered trees that predominates in central Tanzania. From the beginning of the first millennium B.C., the Great Rift Valley served as a highway along which immigrants passed into the northern and western parts of what is mainland Tanzania. By the early 1880s, a newly unified Germany was searching for economic lebensraum and a political place in the sun vis-à-vis other European powers.
