No one doubts that after two centuries or so of Muslim rule in Sicily, conquest, migration and settlement were fundamentally important in forming the largely Arabic-speaking and Muslim population whom the Normans found when they arrived in 1061. But in spite of only fragmentary primary sources, many have long suspected that migration patterns are not enough to account for this change on their own. In response, this article presents a framework of historical process arguing that Sicilian Muslim communities also absorbed Greek-rite Christians into extended kin-groups who acculturated into an increasingly insular and melting-pot society shaped by a ‘patriarchal state’. From the 1030s, when that Muslim state began to collapse, political re-alignment foreshadowed a broadly parallel socioreligious reconfiguration. Sicilian Muslim and Christian factions allied with knights from the Italian mainland, but, during the better documented 1100s, the Muslim communities underwent rapid dissolution in an increasingly Christianised state and society. The paper concludes that those positioned along the old Muslim–Christian peripheries¬ – liminal groups and individuals around which politics and religion had always closely related ¬– could operate both within and across religious and linguistic communities. As such, they assumed far greater importance in times of political uncertainty and transition, most visibly during and after the Norman Conquest, spearheading wider change as they did so.