Modern commodity markets
Despite the shift to fiat money, and credit money, direct commodity trade and barter has always remained active in the background in some form or another, and seems to have been revived due to global capitalism, wherein nearly every currency is widely traded as a commodity.
Traditionally, "money-changing" or "banking" was one of the prime functions of commodity markets. The key difference between the ancient and modern commodity markets appears to be degree to which banking and clearing has been separated and regulated by consent of many governments which have surrendered some national sovereignty to enable the Bank for International Settlements, for instance, to back currencies in global trade, establish common risk and reserve standards, and, in the words of its chairman Andrew Crockett, "hardwire the credit culture". With credit concerns minimized or at least standardized, the commodity markets can then trade equity in enterprises as a "stock market", national currencies in a "money market", and everything else in a "commodity market" of its own.