Some interesting exceptions have come from scholars who are not, in the first instance, historians of Islam. Important comparative work has been done in environmental and ecological history and related areas. But in the end it seems that many historians prefer not to describe the early Islamic polity as an empire at all.
Behind this reluctance lies a tendency to view the early Islamic polity as Sui Generis and thus beyond comparison. Indeed, it is often proposed or assumed that Islam’s founding structures and principles were unique to it and marked it off from other empires and polities. In this way a kind of “Islamic exceptionalism” has planted itself in scholarly discourse and public opinion.