646) by the lieutenants of the caliph Othman, and was constituted the capital of Khorasan.
The reign of the third caliph Othman (644-656) was marked by the beginning of that internal strife which was to ruin Arabia; but the foreign conquests continued.
After the murder of Othman, `Ali (656-661) became caliph, but Moawiya, governor of Syria, soon rebelled on the pretext of avenging the death of Othman.
Othman was less careful, and allowed a fleet from Africa to help in the conquests of the aevant and Asia Minor.
In his appointments to governorships and other offices, as well as in his distribution of spoil, Othman showed a marked preference for the members of his own tribe the Koreish (Quraish) and the members of his own family the Bani Omayya (Umayya).