By about 1200, Zimbabwe was occupied by prominent Karanga chiefs, who erected in the valley below the Acropolis the immense elliptical structure known as the Great Enclosure. Zimbabwe's rulers bartered copper and gold from mines under their control with traders from the east African coast. Fine metal ornaments of African manufacture as well as imported glass beads and Chinese porcelain litter the deposits of the site. People no longer lived at Zimbabwe after the middle of the fifteenth century probably because soil fertility declined and erosion from over intensive cultivation set in. There is evidence that the site continued to be an important religious shrine for some time after that however.
Cattle based societies surround the Great Zimbabwe center.
The real wealth of those who ruled the grassland plateau country around Zimbabwe lay in cattle. They were in effect Big Men who redistributed wealth. Cattle-raising societies tend to be relatively unstable since hers can easily be rustled away by rivals. It was due to this fact that power bases shifted on a more or less regular basis in these societies. Two kingdoms, Nyoro and Nkore, in the region of what is now Uganda rose in East Africa.