In the year 1000 the export goods from Africa—apart from slaves—that passed through Cairo included ivory, copper, bronze, and most alluring of all, gold. A major mystery of the era was identifying the origin of the gold—learning not just where the mines were located but identifying who controlled the mines and who sold the gold they produced. Because this knowledge could allow the bearer to challenge the middlemen who ran the gold trade, the middlemen did everything in their power to prevent outsiders from learning how they operated. They kept their secrets for centuries.
