Denariii is the main currency used in the Ancient World. There are many other currencies used in the Ancient World but the denariii is primarily used in the Mediterranean by way of the Empire of Latium.
During the events of The Blue Madjai, Harnuphis mentions to Iya that she thought she would have to sell her belongings because the Denariii doesn't travel far, in which Iya scoffs the currency saying it doesn't go far in Wagadu Mandé and going as far as calling it "barbaric".