"The flourishing caliphate empire established regular trade relations with both Asia and Europe, with the Italian seaboard republics of Venice and Genoa in particular amassing great wealth through their trade with the Orient. The trade cities of the Eastern Roman Empire and Moorish Spain were also centres for the exchange of goods between the Occident and Orient."
http://www.dailyislam.info/the-encounter-between-the-merchants-and-crusaders/
http://www.dailyislam.info/the-encounter-between-the-merchants-and-crusaders/