When the Vandals invaded Rome they discovered warehouses loaded with spices, silks, and expensive goods from the Far East.
Romans had only a vague idea of where these costly goods had come from. It was a trade secret. All they knew was that they had come from somewhere on the other side of the the deserts beyond the borders of the Roman Empire. Those who did know didn’t talk.
The thing that everyone understood was that a pound of pepper was worth a pound of gold. The spice trade delivered coveted goods, and bags and chests of gold and silver were returned in payment. Rome was drained of its gold and silver. Someone on the other side of the desert collected it. At the last, Rome had no gold and was forced to adopt the barter system. The spice merchants in the Far East owned the world’s supply of gold. That gold allowed the spice merchants to buy anything that gold will buy – priests, kings, armies – anything!