 Complete the following phrase:  Among the most gifted governors of the Umayyad era, Ziyad had a good understanding of his task as governor, and had a great influence on his successors concerning the conception of the duties of rulers, according to Hasson. According to Kennedy, Ziyads settlement of Iraqi Arab troops in Khurasan had extremely important consequences for Islamic history as the descendants of those settlers, who were known as ahl Khurāsān, 