Azerbaijan maintained its national character after its conquest by the Arabs in the mid-seventh century a.d. and its subsequent conversion to Islam. At this time it became a province in the early Muslim empire. Only in the 11th century, when Oghuz Turkic tribes under the Seljuk dynasty entered the country, did Azerbaijan acquire a significant number of Turkic inhabitants. The original Persian population became fused with the Turks, and gradually the Persian language was supplanted by a Turkic dialect that evolved into the distinct Azerbaijani language. The process of Turkification was long and complex, sustained by successive waves of incoming nomads from Central Asia.