'Abd al-'Azīz b. Marwān (d. 86/705) reigned as the amīr of Egypt and walī al-'ahd (heir apparent) to the Islamic caliphate for over 20 years. This book intends to revive this largely forgotten amīr and demonstrate the critical role he played in the formation of the Marwānid dynasty. The founding thesis of this study is that 'Abd al-'Azīz was appointed the amīr of Egypt and second heir apparent due to the legitimacy his maternal lineage brought the nascent dynasty.