ABSTRACT Population movements were a regular feature in Iberia across the medieval period, especially due to the conflicts for land control between the northern Christian states and Islamic powers in the south. Movements of Muslim populations caused by the Christian expansion rose sharply from the eleventh century and peaked over the following two centuries. Drawing on the Arabic sources, this article explores how, when, and where the Muslims had to leave their homelands following the arrival of Christian conquerors. While documentary information is scarce and lacking in detail, these sources are key to understanding the real demographic impact caused by the expansion of Christian kingdoms into Islamic territory in Iberia across the eleventh through thirteenth centuries.