The Jewish people participated in commerce in the countries of western Mediterranean . However, Jewish roles in commerce were rather limited because Syrian merchants in Gaul who supplied the population with luxury articles imported from the East monopolized the whole commerce scene . There would be a consistent war between Muslim and Christian fleets at sea, which left the Jewish merchants at a neutral status. As a result, Jewish merchants who were kidnapped at sea by pirates had a better chance of getting their ransom paid by their co-religionists . Jewish merchants had become very competitive which supposedly put some fear on others. Consequently, in 945, the Venetian government ordered its ship owners not to carry Jewish passengers .
Jewish merchants traded in amber, textiles, hides, arms, spices, precious stones, and other luxury articles . Their clientele consisted mainly of royal and ducal courts and the aristocracy, both secular and clerical . There were other groups engaged in international trade, and Jewish merchants were not the dominant role in the commerce scene . In the cities re-conquered from the Muslims in Spain, Jews played a decisive role in the revival of commerce and industry, and especially in the production and merchandising of clothing . As well, England's Jewry had a role in commerce, too .
After the year 1100, The Jewish role in international trade began to decline . The Hansa cities began to replace the Jewish traders. Their ships were heavily armed, and were no match for the Jews .
Some believe that Jews