and subordinate to, the central government at Byzantium, and constantly recruited by Byzantine officials, at least in their upper grades. The Persian government, on the other hand, was a self-contained one, fully organised throughout and including the supreme and central authority. Until the fall of the 'Umayyads, after which Persian influence became supreme, the political structure of the Muslim state was somewhat experimental; apparently the rulers left the details altogether to the subordinate officials who adapted to the needs of the state such elements as they could use from the old provincial administration.
In the matter of taxation the early Khalifate continued the system already in vogue and employed existing methods for the collection of the newly imposed poll tax. It was on this side that the 'Umayyad rule was most unsatisfactory. Like many who have been bred in poverty and have afterwards suddenly come into great wealth, the Arabs behaved as though their wealth was inexhaustible: each governor bought his appointment from the state and it became a recognised custom for him to exact a cash payment from the outgoing governor, and then he was free to raise what he could from his defenceless subjects to prepare for the day when his opportunities of exaction came to an end. The thoroughly unsatisfactory condition of the 'Umayyad financial system was one of the leading causes of their fall. One of the 'Umayyad sheikhs, named Minkari, when asked the reason of their fall, replied:—
