In August 909, ʿUbayd Allāh was acclaimed caliph by the Kutama forces at Sijilmasa, a pivotal step in transforming an underground missionary movement into a proclaimed caliphate.
Al-Mahdi arrived in Ifriqiya and, upon entering Raqqada, publicly proclaimed himself caliph with the regnal title al-Mahdī bi-llāh, a foundational moment for the Fatimid Caliphate’s legitimacy and administration.
By 912, al-Mahdi began seeking a more secure and strategically positioned capital on the coast, partly to reduce tensions with the predominantly Sunni inland center of Kairouan and to strengthen maritime defense.
Construction began on the fortified palace city al-Mahdiyya (Mahdia) in 916, alongside the initiation of its congregational Great Mosque, anchoring the dynasty’s new political-military center on the Mediterranean coast.
Al-Mahdi died at Mahdiyya on 4 March 934; he was succeeded by his son al-Qāʾim bi-Amr Allāh, marking the end of the founding caliph’s reign and the transition to the next phase of Fatimid expansion and consolidation.
Founding of the Fatimid Caliphate in Ifriqiya under al-Mahdi Billah (909–934)
