A young Bantu man by the name of Bakari stood on the shores of the southernmost coast of Africa. He was the son of his tribe's chieftain and was next in line to inherit his father's position. Currently, he was gathering shells with the intention of trading them to the tribe's craftsman in exchange for the item which the local hunter desired for his meat.
Africa was a large continent with many diverse cultures, however after you reached a certain point southward of the Sahara, they devolved from fledgling civilizations to hunter-gatherer tribes. Because of this, the idea of currency was foreign to Bakari and his people. Instead, they relied on the more primitive system of bartering.