Islam had spread throughout the west Sahara by the eleventh century under the influence of Berber and Arab traders and occasional Arab migrants.

Nevertheless, traditional religious practices thrive.

The conquest of the entire west Saharan region by the Almoravids in the eleventh century makes possible a more orthodox Islamization of all the peoples of Mauritania.

The breakup of the Sanhaja Confederation in the early eleventh century leads to a period of unrest and warfare among the Sanhaja Berber groups of Mauritania.

In about 1039, a chief of the Djodala, Yahya ibn Ibrahim, returns from a pilgrimage to Mecca bringing with him a Sanhaja theologian, Abdallah ibn Yassin, to teach a more orthodox Islam.

Rejected by the Djodala two years later, after the death of Ibn Ibrahim, Ibn Yassin and some of his Sanhaja followers retire to a secluded place where they build a fortified religious center, a ribat, which attracts many Sanhaja.

In 1042 the murabitun (men of the ribat), as Ibn Yassin's followers come to be called, launch a jihad, or holy war, against the non believers and the heretics among the Sanhaja, beginning what later becomes known as the Almoravid movement.

The initial aim of the Almoravids is to establish a political community in which the ethical and juridical principles of Islam will be strictly applied.

First, the Almoravids attack and subdue the Djodala, forcing them to submit to Islam.

Then, rallying the other Berber groups of the west Sahara, the Almoravids succeed in recreating the political unity of the Sanhaja Confederation and adding to it a religious unity and purpose.

By 1054 the Almoravids have captured Sijilmasa in the Maghreb and have retaken Aoudaghast from Ghana.