Abd al-Mu’min was an Algerian Berber of the Zenata tribe, born in 1094 CE. He was studying Fiqh, “full understanding”or the study of Islamic law, when his teacher died. The students had heard of Abu Abd Allah Muhammad ibn Tumart, a fiery preaching scholar who had studied in Cordoba, Baghdad, and Alexandria – three of the greatest cities of learning in the world. They wanted him to be their new teacher. Abd al-Mu’min was sent with a letter to persuade ibn Tumart to settle in Tlemcen. Ibn Tumart wouldn’t be put off his path towards Morocco, but he invited al-Mu’min to become his follower (~1117 CE). As they journeyed, ibn Tumart preached on the steps of mosques and courthouses, destroyed the merchandise of wine and pork merchants, and condemned and even assaulted women for not veiling. They were hustled along from one city to the next.
By 1120 they took to the Sous Valley, on the opposite side of the High Atlas Mountains, to escape arrest. The following Ramadan ibn Tumart announced to his ten followers that he was the Mahdi, a messianic imam of supreme purity and wisdom from the House of Muhammad. They believed him and confirmed this revelation, and helped him establish a tiny emirate in the mountains. Ibn Tumart and al-Mu’min made alliances with the other anti-Almoravid tribes in the High Atlas and Anti-Atlas Mountains, and created a hierarchy and system of succession. The first ten followers were ranked highest, followed by a council of forty from important tribes, followed by a third body before the whole mass. They built a fortress high in the mountains called the Tinmel where they lived and trained. Almohad riders disrupted the trade routes between the mountains, diverting gold from west Africa intended for Morocco.
In early 1130 the Almohads made their first direct assault on an Almoravid city, Aghmat. Most of the Almohad leadership was wiped out, including their general. Ibn Tumart died that August in the fortress compound. Al-Mu’min was an outsider in the Sous Valley, from a different tribe and tribal confederation. He was uncertain the others would accept his leadership after ibn Tumart’s death, so he kept it secret for two or three years while cultivating relationships, before officially taking over as the head of the Almohads.
Al-Mu’min was the student who took his master’s teaching and built it into an empire. First conquering the High Atlas and Middle Atlas, he made a caliphate in the mountains that stretched north to Algeria. Reverter de La Guardia I was the Viscount of Barcelona and a mercenary hired by the Almoravids as protector. His Christian army kept the Almohads in check for years, but he died in battle in 1142 or 1144. His corpse was crucified by enemies after. Al-Mu’min and his forces were able to take Marrakesh by 1147, and the war quickly turned in their favor from there. The Almohads made their base at Marrakesh, after tearing down temples and mosques they found too lavish.
They expelled 30,000 residents from Marrakesh – Jews, Christians, or people they thought likely to revolt. Then they turned their expansion efforts eastward, focusing on north Africa. The Almohads conquered Hammadid territory to take Algeria in 1152, and defeated Normans to take Ifriqiya (Tunisia) in 1159. Grenada, Cordoba, and Seville relented to diplomatic shows of force in the early 1160s. Al-Mu’min had a fort constructed in preparation for his arrival in Spain, Ribat el Fath or “Camp of Victory”. He died in 1163 before the campaign could begin. His son Abu Yaqub Yusuf would invade Al-Andalus, and impose a series of Islamic reforms on the entirety of the Almohad caliphate.
Fromherz, Allen J. “The Almohads: The Rise of an Islamic Empire”. I.B. Tauris, 2012.