a1 Historical Monuments Commission, Rhodesia
Two hypotheses are available for the origin of the Zimbabwe culture. A religious hypothesis attributes its development to an African society in isolation, placing it in the class of a primary state. In contrast, the trade hypothesis maintains that it was a secondary state resulting from the gold trade.
If the religious hypothesis is correct, then Zimbabwe would be an exception to all other known cases of primary state formation. The archaeological evidence points to a horticultural subsistence throughout the Iron Age sequence in the area and a small population until Period III/IV. On the other hand, all known primary states were based on large populations and intensive agriculture. It is more likely that Zimbabwe is a typical case of secondary state formation.
The stratigraphy on the Acropolis indicates that a social transition from Period II to III probably occurred at Zimbabwe and was not the result of an immigrant group, and the short chronology places this transition around A.D. 1250. The evidence available from Arab documents, trade imports and ancient mining demonstrates that trade existed well before then. Consequently, the evolution of the Zimbabwe culture was almost certainly due to the Arab gold trade.