This comparative study explores three key cultural and political spheres - the Latin west, Byzantium and the Islamic world from Central Asia to the Atlantic - roughly from the emergence of Islam to the fall of Constantinople. These spheres drew on a shared pool of late antique Mediterranean culture, philosophy and science, and they had monotheism and historical antecedents in common. Yet where exactly political and spiritual power lay, and how it was exercised, differed. This book focuses on power dynamics and resource-allocation among ruling elites; the legitimisation of power and property with the aid of religion; and on rulers' interactions with local elites and societies. Offering the reader route-maps towards navigating each sphere and grasping the fundamentals of its political culture, this set of parallel studies offers a timely and much needed framework for comparing the societies surrounding the medieval Mediterranean.