Uthman's nepotism provoked the ire of the Ansar and the members of the "shura". In 645/46, he added the Jazira (Upper Mesopotamia) to Mu'awiya's Syrian governorship and granted the latter's request to take possession of all Byzantine crown lands in Syria to help pay his troops. He had the surplus taxes from the wealthy provinces of Kufa and Egypt forwarded to the treasury in Medina, which he used at his personal disposal, frequently disbursing its funds and war booty to his Umayyad relatives. Moreover, the lucrative Sasanian crown lands of Iraq, which Umar had designated as communal property for the benefit of the Arab garrison towns of Kufa and Basra, were turned into caliphal crown lands to be used at Uthman's discretion. Mounting resentment against Uthman's rule in Iraq and Egypt and among the Ansar and Quraysh of Medina culminated in the siege and killing of the caliph in 656. In the assessment of the historian Hugh N. Kennedy, Uthman was killed because of his determination to centralize control over the Caliphate's government by the traditional elite of the Quraysh, particularly his Umayyad clan, which he believed possessed the "experience and ability" to govern, at the expense of the interests, rights and privileges of many early Muslims.