This study investigates the evolution and persistence of the caliphate as a functional political institution within the Iberian Peninsula during the tenth and eleventh centuries. David J. Wasserstein, a scholar of Islamic history, utilizes a combination of traditional documentary sources and numismatic evidence to challenge the conventional narrative that the caliphate ceased to be a relevant political force after the fall of the Umayyads in Cordoba. He argues that the institution remained a vital instrument for political legitimacy for various rulers, including the Hammudid dynasty and Slav leaders, well into the eleventh century.

Historians and scholars of Islamic Spain recognize this work as a rigorous re-evaluation of political legitimacy in the region. Readers frequently note the academic density of the prose and the author's meticulous use of coin evidence to support his historical claims.