Silent trade

Cosmas Indicopleustes describes this practiced in Azania, where officials from Axum traded for gold with beef.

Because of this trade, cities grew and flourished and parts of West Africa became commercial centers.

[2] Silent trade might be used because of an inability to speak the other traders' language, or to protect the secrets of where the valuable gold and salt came from.

On reaching this country, they unload their goods, arrange them tidily along the beach, and then, returning to their boats, raise a smoke.

Seeing the smoke, the natives come down to the beach, place on the ground a certain quantity of gold in exchange for the goods, and go off again to a distance.

They usually dealt in bazaars; the vender told the price of his goods in a subdued voice and in few words; the purchaser replied by taking his hand, and by a certain manner of doubling and extending the fingers, explained what abatement he wished in the price.

The bargain was often concluded without speaking a word; and, to ratify it, the hand was again taken in token of its inviolability....Such were the Banyans three centuries gone by, and we have reason to think, they have not been entirely changed.