Under Abd al-Mu'min, the Almohads swept down from the Atlas mountains, eventually destroying the power of the faltering Almoravid dynasty by 1147. Abd al-Mu'min created his empire by first winning control of the high Atlas Mountains, then the Middle Atlas, into the Rif region, eventually moving into his homeland north of Tlemcen. In 1145, after the Almoravids lost the leader of their Catalan mercenaries, Reveter, the Almohads defeated them in open battle. From this point the Almohads moved west onto the Atlantic coastal plain. After laying siege to Marrakesh, they finally captured it in 1147.