In the tenth century, the nominal unity of the Islamic world was split as several competing political entities arose and claimed the legitimacy to lead. The Buyids and the Fatimids are often presented as ruling in isolation from each other during this period, as merely regional leaders. Further, there has been almost no study of their relationship. While they exchanged two official missions during the reigns of the Fatimid Caliph al-‘Aziz (r. 975-996) and the Buyid Amir 'Adud al-Dawla (r. 978-983), each dynasty is often viewed independently, depicted as ruling over its respective territories from Cairo or Baghdad without consideration of their rival Shi’i state. This paper, however, will take a different approach and argue that these two dynasties were acutely aware of the other as rivals and made deliberate attempts to undermine each other’s legitimacy to rule. Through a rhetorical analysis of two Buyid-sponsored histories, al-Miskawayh’s Tajarab al-Umam and the surviving fragments of Abu Ishaq al-Sabi’s Kitab al-Taji, this paper will focus on the Buyid side of this exchange and explain how 'Adud al-Dawla attempted to emulate successful Fatimid policies while minimizing the legitimacy of the Fatimid Caliphs. 'Adud al-Dawla had a complicated game to play in articulating his own right to rule. The Buyids emerged out of the ninth century Zaydi states in Tabaristan and Gilan, but the Buyids later declared their allegiance to Ithna’ashari Shi’ism. Despite this, they maintained the symbolic position of the Sunni ‘Abbasid Caliph while harkening back to pre-Islamic Persianate forms of legitimacy by declaring themselves “Shahanshahs” and linking their rule with Sassanid kings. At the same time, the Buyids also styled themselves as Shi’i leaders through sponsoring Shi’i scholarship, ritual, and practice. When this led to Sunni riots in Baghdad, however, 'Adud al-Dawla began, in the model of the Fatimid Caliph al-‘Aziz, styling himself as a more universal Muslim leader. He pursued accomodationist policies towards the Sunnis and cultivated a closer relationship with the ‘Abbasid Caliph (which led to new religious privileges). Further, he made deliberate attempts to minimize the power and prestige of the Fatimid Caliphs, emphasizing his unprecedented knowledge of events in Fatimid territories while presenting the Fatimid Caliph as a merely regional ruler (“Sahib al-Maghrib”). Examining the interactions between these two dynasties will show how the Buyids began to make broader claims to universal Muslim leadership during the reign of ‘Adud al-Dawla.