Islamic civilization

“In every commercial city—meaning Islamic cities—along the caravan route, there were markets and money changers who carried out the banking activities necessary for trade, such as selling and exchanging currency and issuing financial instruments (similar to modern checks) that merchants carried with them for buying and selling. The money changer would issue the merchant or traveler a letter of guarantee for a specific amount of dinars, enabling him to obtain the necessary funds from the money changer’s agents along the route.”

– Studies in Islamic Civilization (p. 269)