ban. This, rather than religious backsliding, explains the lack of interest in the ban among the contemporary Christian and Jewish counterparts of the Islamic ulema (according to Feisal Khan). (According to two other sources — International Business Publications and Egyptian Grand Mufti Ali Gomaa — riba is restricted to exchanges involving currencies of gold and silver, and so does not apply to loans of paper currency. Thus, when "currencies of base metal were first introduced in the Islamic world", Islamic jurists did not forbid interest charges on them as riba.) Historically, while the Islamic states followed classical jurisprudence in prohibiting an increase in repayments on loans (interest) in theory, in practice the giving and taking of interest continued in Muslim society "at times through the use of legal ruses (hiyal), often more or less openly." One common Ottoman era stratagem to circumvent of the ban on interest, according to Timur Kuran, was known as istiglal and involved the borrower selling his house to a lender and immediately leasing it back. The proceeds of the sale served as the sum loaned, the lease/rent/mortgage payment served as principal and interest repayment of the loan. According to Kuran, only transactions "that satisfied the letter of the ban" on interest "through stratagems" (hiyal) were allowed. In addition, in the sixteenth century, an Ottoman sultan "limited the annual rate of interest to 11.5%" "throughout the empire" on these loans. This order "was duly ratified by a legal opinion (fetva)." Another source (Feisal Khan) quotes several sources indicating the Ottoman empire forbid as riba only interest rates above a certain level (about 10-20%). According to Minna Rozen the business of money lending was completely in the hands of Jewish Sarrafs in the Ottoman Empire. Europeans who visited Ottoman Empire stated that Ottoman economy would not function without these Sarrafs, though they sometimes were accused of cheating. In Persia, money lending was also dominated by Jewish Sarrafs. In nineteenth century Shiraz, for example, almost all Jews were active in lending money on interest. Taqi Usmani maintains that outside of Dar al-Islam, riba (interest on loans) allowed the Rothschild family to "acquired financial mastery over the whole of Europe and the Rockfeller [sic] over the whole of America". Modernism The orthodox prohibition on interest was reconsidered by Islamic Modernists starting in the late 19th century in reaction to the rise of European power and influence during the Ages