During the Umayyad khilafah (661-750) state revenues came from several sources. The state treasury received one-fifth of the spoils of war, mostly in the form of movable booty, which was called fai'. In addition, when a city surrendered to Muslim troops and negotiated a treaty with them, it often agreed to pay an annual tribute. The khilafah also levied taxes. Non- Muslims paid jizya (poll, tax) and kharaj (agricultural produce tax). Levied on able-bodied males, usually between eighteen and forty-five years old, jizya was regarded as payment for military protection, in lieu of y service, and the amount varied according to the wealth of the individual. The kharaj varied according to the type of crop, the distance from the market, and the type of irrigation used to cultivate it. Some crops were exempted from taxation. Arab Muslims paid the...