This chapter explores and juxtaposes the discussions of Byzantium and the Byzantine-Ottoman institutional (dis)continuity as well as the evolving attitudes towards cultural material heritage in the late-Ottoman and early Republican Turkish historiography. During the last decades of the Ottoman empire, the presentations of the Byzantine institutions and material heritage and the assessments of their importance for the Ottoman successor were characterised by considerable plurality, compared to the early Republican (Kermalist) period, when the robustly ethnocentric ‘Turkish History Thesis’ came to overpower the Turks’ historical imagination. The influential work of Mehmet Fuat Köprülü, rejecting Byzantine influence on the Ottomans, and his contribution to the Turkification of Ottoman imperial history is discussed.