Historical comparison is a delicate practice that requires a certain methodological rigor. This is particularly true for historians who intend to compare and contrast two successive political systems in the same geographical area. By playing with the chronological and geographical scales and shifting the historical viewpoint, distinctive features and key elements can emerge from such a comparison. Therefore, across the Mediterranean Basin during the premodern history of Islam, the people whom Jean-Claude Garcin called the “nouveaux peuples de l’Islam” came into power in the eleventh through thirteenth centuries.