It is often mistakenly assumed that Mozarab merchants forged a vital commercial and cultural link between the north and south across the Iberian frontiers. Mozarab refugees may have had influence in northern Iberian trade at places like Toledo, but there is no reason to believe that they engaged in commerce with their abandoned homeland. Most traffic between Al-Andalus and Christian regions remained in the hands of Jewish and Muslim traders until the dramatic shifts initiated by European commercial expansion throughout the 11th and 12th centuries. With the development of Italian maritime power and southward expansion of the Christian Reconquista, Andalusi international trade came increasingly into the control of Christian traders from northern Iberia, southern France, or Italy and by the middle of the 13th century was an exclusively Christian concern.