 At the same time, his response to the Byzantine–Christian resurgence and the criticism of Muslim religious circles, which dated from the beginning of Umayyad rule and culminated with the outbreak of the civil war, was to implement Islamization measures.The centralized administration he established became the prototype of later medieval Muslim states.In Kennedy's assessment, Abd al-Malik's "centralized, bureaucratic empire... was in many ways an impressive achievement", but the political, economic and social divisions that developed within the Islamic community during his reign "was to prove something of a difficult inheritance for the later Umayyads".