Abd al-Mu'min ibn Ali al-Kumi was the first Almohad caliph and the political and military architect of the Almohad empire, the largest single Berber-ruled state in history. He was born around 1094 among the Kumiya, a small Zenata Berber tribe of the western Algerian coast near Tlemcen, and was educated in Tlemcen before joining Ibn Tumart's circle in the High Atlas around 1117.
Ibn Tumart designated Abd al-Mu'min as his successor on his deathbed at Tinmel in 1130. Over the following seventeen years Abd al-Mu'min consolidated the Almohad movement, restructured the Masmuda tribal hierarchies into a permanent military and administrative system, and conducted the campaign that broke the Almoravid empire. He took Marrakesh in March 1147 after a year-long siege, executed the last Almoravid caliph Ishaq ibn Ali, and proclaimed the Almohad caliphate as the legitimate successor to the Almoravids.
His subsequent reign extended Almohad authority eastward across the central Maghreb (Tlemcen 1145, Bijaya 1152), into Ifriqiya (Tunis 1159), and across the southern Mediterranean to Tripolitania, with simultaneous campaigns into al-Andalus that took Cordoba and Seville from the post-Almoravid taifas. By his death in 1163 the Almohad empire had reached its full extent: from the Atlantic to the borders of Egypt, from the Sahara to central al-Andalus.
Abd al-Mu'min institutionalised Ibn Tumart's theological project, undertook the standardisation of Almohad religious instruction across the empire, and patronised the early careers of the philosophers Ibn Tufayl and Ibn Rushd (Averroes). His succession by his son Yusuf I in 1163 inaugurated the dynastic phase of the Almohad caliphate that would last until 1269.