Yusuf ibn Tashfin was the Almoravid emir who built an empire spanning Morocco and al-Andalus, founded Marrakesh, won the Battle of Sagrajas in 1086, and then absorbed the taifa kingdoms of Muslim Spain.
Yusuf ibn Tashfin was the emir who made the Almoravids a great power. A Sanhaja Berber from the Sahara, he unified Morocco, founded Marrakesh as his capital, and took the title Amir al-Muslimin, "Commander of the Muslims".
Summoned into Iberia by the taifa kings after the fall of Toledo, he defeated Alfonso VI at Sagrajas in 1086 and, returning in the following years, deposed the taifa rulers and annexed al-Andalus to his empire — decisively altering the course of the Reconquista.
Rising within the austere, reforming Almoravid movement of the western Sahara, Yusuf extended its power across Morocco and the Maghreb, founding Marrakesh around 1070 as the seat of his authority. By the 1080s he ruled the strongest state in the western Islamic world.
When al-Mutamid of Seville and the other taifa kings, unable to resist Alfonso VI, appealed for aid, Yusuf crossed the strait and won the great victory of Sagrajas in 1086. Judging the taifa rulers weak and impious, he returned to depose them one by one, uniting Muslim Iberia under Almoravid rule before his death in 1106, when his son Ali ibn Yusuf succeeded him.
The sources portray Yusuf as austere, disciplined and shrewd — a leader of a puritanical movement who lived plainly even as he ruled an empire, and who judged the luxurious taifa kings as much for their impiety as their weakness. His patience in consolidating the Maghreb before intervening in Iberia marks a careful strategist.
He was also ruthless in pursuit of unity, turning on the very rulers who had invited him and stripping them of their kingdoms. To Andalusi and Christian observers alike he was a formidable and unsentimental figure, the embodiment of a new and harder power from across the strait.