 The taxes instituted were the kharaj—a tax that landowners and peasants paid according to the productivity of their fields—as well as the jizya—paid by non-Muslims in return for protection under the Muslim state and exemption from military service.The Byzantine civil service was retained until a new system could be instituted; therefore, Greek remained the administrative language in the new Muslim territories for over 50 years after the conquests.The relations between the Muslims and the Christians in the state were good.