Both Abu Abd Allah Muhammad ibn Tumart, the ‘Prophet’, and his general, Abd al-Mumin ibn Ali al-Goumi, were Berbers, but they came from the mountains, not the desert. Ibn Tumart came from the northern side of the Anti-Atlas. In about 1106 he began a pilgrimage to Mecca but, instead of completing it, studied in Baghdad or Damascus. He came into contact with both mainstream Sunni theology and Sufism and returned home with the idea of reforming the religion and the morals of the Maghreb. On the way, he met Abd al-Mumin and joined him in a mission of reform. He arrived in Marrakesh, but the Almoravids disliked his social criticism, and Ibn Tumart fled to Tinmel, high in the High Atlas where he built a following.
Ibn Tumart’s teaching was more spiritual than the Almoravids’: he said God was pure spirit, absolute, and unitary. His followers called themselves al-Muwahhidun (unitarians, or believers in the oneness or unity of God), anglicized as ‘Almohads’. The Almoravids, he said, were polytheists because they believed in God’s corporeal nature, but like them, he proposed an austere and moralistic Islam that drew on Shiite ideas of the hidden imam. Ibn Tumart announced that he was the Mahdi, the eschatological redeemer who will return before the Day of Judgment. His followers were highly motivated by the idea of proselytizing for this idea. During the 1120s, Ibn Tumart extended his authority from Tinmel but could not take Marrakesh before he died, in 1130. In 1133, Abd al-Mumin took over the leadership, occupying first the mountains and then the cities on the plain. In the early 1140s, the Almoravids took northern cities, including Taza, Ceuta, Meknes, and Salé. Marrakesh fell last, after a long siege, in 1147. Once the city fell, it was plundered, and Abd al-Mumin declared that all the religious buildings were incorrectly oriented towards Mecca and must be replaced.
Once Morocco had been conquered, Muslims in the Iberian Peninsula turned to them for help against the renewed Christian advance. In 1145, Abd al-Mumin sent troops to occupy most of Islamic Spain and began to turn the Christian tide. He also moved east into Algeria and Tunisia. He died in 1163, preparing to embark another army for Spain. At the end of the civil war that followed, Abu Yaqub Yusuf (Abd al-Mumin’s son) beat off his rivals and occupied the remaining portions of Muslim Iberia. In 1195, he won a great victory over the Castilians at Alarcos, in the modern province of Ciudad Real, and stopped the Reconquista in its tracks.
This was the highpoint of the regime’s power and culture. The vigorous intellectual life in Marrakesh attracted international scholars, such as Muhammad ibn Rushd (known in the West as Averroës) and Abu Bakr Muhammad ibn Tufail, author of a philosophical novel, Hayy ibn Yaqzan. Almohad architecture was massive, with huge mosques and impregnable fortifications. The Kutibiyya (Koutoubia) mosque, built on the ruins of the Almoravids’ palace, had a minaret 67.5 metres tall. The minarets at Seville, the Giralda, and the Tour Hassan in Rabat, begun but never completed, had even larger square minarets, which became the style in North Africa. Their Andalusian architects also built huge fortresses, such as the Kasba of the Udayas at Rabat.
All this building was expensive, but the Almohads were rich because they developed the economy, particularly agriculture, the desert trade was extremely important, and the gold coinage was of such high quality that it was used on both sides of the Mediterranean. But the economy was more fragile than it appeared. During the reign of Mohammed al-Nasir (r.1199-1213) there was war on two fronts, with remnants of the Almoravids and, in Spain, with the united Christian kings who inflicted a crushing defeat on al-Nasir’s army at Las Navas de Tolosa in 1212. By 1266, the whole peninsula was in Christian hands, except Granada. The great Almohad army was dismembered, so taxes could no longer be collected. The dynasty began to squabble amongst itself, and tribal confederations such as the Banu Marin challenged its authority, although it struggled on in Marrakesh until 1269.