During the Middle Ages several methods of payment existed, each one nearly equal to the other: money, trade, and favors. In Prosperity your Treasurer will be able to barter specific resources to obtain others, or you will be able to exchange land for military aid, or even simply use the popular monitary unit of not only fifteeth century central Italy, but throughout Europe of the time: the Fiorino.
The gold Fiorino typically weighed 3.54 grams of pure 24 karat gold and was grouped with two other coins of lesser value.
The silver Fiorino, also called the Grosso (Large) or Popolino (Of the People), valued at 1/20 the worth of the gold Fiorino.
The copper Fiorino, also called the Fiorino Nero (Black Fiorino) due to the color which was typical of the oxidation at the time, with 1/12 the value of the silver Fiorino.
The face of the Fiorino was commonly the Lily of Florence, while the back of the coin had the effigy of Saint John, the patron saint of the city.
If you are a good Lord, you will see many Fiorini deposited by the towns people, thanks to the taxes that your Treasurer and his emissaries will collect in your name. Several standard taxes of the Middle Ages include: Hearth (Focatico), Tithe (l’Imbottato), and Fodrum (Fodro). The first includes a tax on every fireplace, or rather each family unit, the second is a tax paid on agricultural products, and the third, more so than a tax, is an obligation to host the emperor, his officials, and his troops should they be of passing. In such a case, subjects would be expected to provide food and accommodation without anything in return, so pray that you do not receive any visits! All of these small details together with many others richly reconstructed within the game, favor the realism and identification within the medieval economy, enthusiastically luring the player into every aspect of life in the Middle Ages, even reaching the bureaucracy!