Ahmad bin Yahuya al-Baladhuri's History of the Arab Invasions is perhaps the most important single source for the history of the great Arab conquests of the Middle East in the sixth and early seventh centuries. The author, who died in 892, was a historian working at court of the Abbasid caliphs in Baghdad. He had access to a wide variety of earlier writings on the conquests and has preserved accounts that are not found anywhere else. But the book is much more than a series of accounts of battles. Baladhuri was very interested in the origins of the Islamic state and its institutions. His work...