In 346/957, Abū Manṣūr Muḥammad b. ‛Abd al-Razzāq Ṭūsī commissioned his vizier Abū Manṣūr Ma‛mārī to compile a Shāhnāma in prose, approximately twenty years before Firdawsī began his history of pre-Islamic Persia in verse. In the preface, Ma‛mārī included a genealogy of his patron and of himself, both of which led back to the Kanārang (“Lord of the Eastern March”) under the Sāsānian Shāhanshāh Khusraw II. Through this lineage, Abū Manṣūr Ṭūsī claims the rights to rule both Ṭūs, which had been given to the Kanārang by Khusraw II, and Nīshāpūr, which the Arab governor ‛Abd Allāh b. ‛Āmir b. Kurayz gave to the Kanārang when he and his son negotiated the surrender of the city’s quhandiz. Why did Abū Manṣūr Ṭūsī need to reassert these rights and why did he choose to do so through a history of pre-Islamic Persia? Abū Manṣūr Ṭūsī’s position had become tenuous in Khurāsān after the Sāmānid Nūḥ b. Naṣr began replacing governors with hereditary claims to the land with Turkish military commanders. Ṭūsī twice fled Khurāsān to join the Būyids in opposition to these moves by the Sāmānids. In 349/961, he lost his titles once and for all to Alptigīn, the founder of the Ghaznavids. The story of Abū Manṣūr and his Shāhnāma highlights a transformation in the eastern frontiers of the Islamic world in the fourth/tenth century, one that many would assume had come centuries earlier with the Arab conquests, the breakdown of the Sāsānian social order and its replacement with a foreign ruling class. Despite the changes that were brought by the Arab conquests, the social and political order of Khurāsān and Transoxania appears to have retained much of its Sāsānian form with local dynasties whose authority was derived from the pre-Islamic past holding on to power. This paper will examine the means by which local elites like Abū Manṣūr Ṭūsī used the pre-Islamic past to justify their authority and how the increasing power of the Turkish military elite finally broke these patterns centuries after the collapse of the Sāsānian Empire.