 The Islamization of Mauritania was a gradual process that spanned more than 500 years.Beginning slowly through contacts with Berber and Arab merchants engaged in the important caravan trades and rapidly advancing through the Almoravid conquests, Islamization did not take firm hold until the arrival of Yemeni Arabs in the 12th and 13th centuries and was not complete until several centuries later.Gradual Islamization was accompanied by a process of Arabization as well, during which the Berber masters of Mauritania lost power and became vassals of their Arab conquerors.