Abstract
The current study affirms that fals were important currency in the Islamic monetary system. The state paid to them a similar interest to that of the main currency (dinar and dirham). This was greatly manifested by the interest paid by the Umayyad state when the pure Arab type of fals was introduced that had a fixed exchange rate for the dirham and was directly supervised by the state. Additionally, the state exploited their diffusion and using them as a subsidy to dinar and dirham. They were also utilized as a fast media and a formal document used by people to ask for their rights if exploited.