Common now.. educate yourself a bit more on this matter. Up for grabs if internet visits you much 😊
'It was more than 5,000 years ago that primitive commodity money was used in Mesopotamia, and it's been over 3,000 years since metal coins began circulating. For more than 99.2% of human civilization, money actually meant something… right up until 1971 when Richard Nixon ended any remaining link between the dollar and gold.' *business insider
Mesopotamia used credit that was fiat in nature... not commodity money. They recorded debts on tally sticks (which could be traded much like bonds currently are). The debt wasn't backed by a commodity. Debt began to be backed by a commodity when coinage began circulating. Due to people confusing the coin which was meant to reflect a magnitude of debt with the wealth it represented. Both the original form of credit and the coinage that followed was fiat in nature. Free market money comes much later