During the Middle Ages in Europe, many cities and towns issued their own coins, often carrying the face of a ruler, such as the regional baron or bishop. When outsiders, especially traveling merchants, visited towns for a market fair, it became necessary to exchange foreign coins to local ones at local money changers. Money changers would assess a foreign coin for its type, wear and tear, and validity, then accept it as deposit, recording its value in local currency. The merchant could then withdraw the money in local currency to conduct trade or, more likely, keep it deposited: the money changer would act as a clearing facility.