Abdallah ibn Yasin al-Jazuli was the Maliki jurist and spiritual founder of the Almoravid movement among the Sanhaja Berbers of the western Sahara. Sent about 1040 from the Sus at the request of the Gudala chief Yahya ibn Ibrahim, he preached a severe Sunni orthodoxy to the Gudala and Lamtuna, who were then only lightly Islamized and still held to older ancestral practices. In the religious memory of the Bidan he stands at the head of the region's conversion: the master of the ribat, the frontier retreat whose discipline forged the desert warriors who carried Islam across the Sahel and into al-Andalus, and from which the community took its name, al-murabitun, 'those of the fortress.' He fell in battle against the Barghawata of the Atlantic plain in 1059.