 Traveling to Morocco, he established a military monastery or ribat where he trained a highly motivated and disciplined fighting force.In 1054 and 1055, employing these specially trained forces, Almoravid leader Yahya ibn Umar defeated the Kingdom of Ghana and the Zanata Berber.After Yahya ibn Umar died, his brother Abu Bakr ibn Umar pursued the expansion of the Almoravids.