Fiat currency was the first currency, developed in Mesopotamia as an accounting system run by the temple-governments of their city-states. Accounts were record

Fiat currency was the first currency, developed in Mesopotamia as an accounting system run by the temple-governments of their city-states. Accounts were recorded in clay ledgers, and withdrawals could be made in the form of clay tokens that could be traded within cities and between cities (i.e. accepted for deposit by the temple of another city-state). A large trading network developed based on that money. The entire system was backed by the authority of the governments to levy taxes (mandatory offerings to the temples), collect debts, and resolve disputes (the same things that back our modern fiat currencies).