During medieval time in Europe, many city or town issued their own coins, often carrying the face of the ruler, such as baron or bishop. When outsider, especially travelling merchants, visit town for a market fair, it became necessary to exchange his foreign coins to local one at local money changers. Money changers assessed foreign coins for its type, wear and tear and possible counterfeit, then accept it as deposit, recording its value in local currency. Merchant then could withdrew the money in local currency to conduct trade or, more likely, kept deposit and use its clearing facility to conduct trade. In market, most large transaction are done, not by cash/coins, but by transfer order of funds on books kept at the local money changer(s). Once the market/fair ends, merchants gathered at the local money changers, then withdrew their deposit in their own different currencies. The rate of exchange between different foreign currencies and the local one are fixed between the opening and the closing days of the market. As the size and the operation of money changer grew, they begin to provide lending facility, hiding the interest rate in foreign exchange rate transaction. This was necessary due to Catholic Church's prohibition against usury.