"Other historical factors which affected the position of the Jews in Islam were the revival of Greek learning and especially the development of the India trade. The new Jewish prominence in medicine and phar­macy was probably due to their deep involvement in both the transmis­sion of Greek science and the trade with India and the Far East simulta­neously.77 In the ninth-century Abbasid caliphate, as we have seen, the India trade became the foundation of the international economy, con­tributing also to a tremendous upsurge of internal commerce and, sub­sequently, the shift towards a unified bi-metallic currency system which encompassed the eastern and western caliphates. At this point, the cen­tral and hegemonic position of the Babylonian Jewry gave them a head­ start not only in the long-distace trade with India but in the organization of finance and also state finance generally.... The great Jewish banking houses of Baghdad also financed the Jewish radhanlya trade which extended - both overland and by sea - from Western Europe to the Middle East and to Sind and Hind and China."