Al-Mahdi

Abū ʿAbd Allāh Muḥammad ibn ʿAbd Allāh al-Manṣūr (Arabic: أبو عبد الله محمد بن عبد الله المنصور; 744 or 745 – 785), better known by his regnal nameal-Mahdi (المهدي, "He who is guided by God"), was the third AbbasidCaliph who reigned from 775 to his death in 785. He succeeded his father, al-Mansur.

His reign saw great architectural achievements including the expansions and reconstructions of the three holiest mosques in Islam, which included the expansion of the Prophet's Mosque in Medina, the reconstruction of Al-Aqsa Mosque when it consisted of fifteen aisles and a central dome, which is bigger than the current Fatimid-era seven aisles layout, and the expansion of the Masjid al-Haram in Mecca, which saw the greatest expansion until it was surpassed by the modern Saudi expansions.

Administratively, al-Mahdi expanded the government bureaucracy, promoted the cultural and economic growth of Baghdad, and renewed military campaigns against the Byzantine Empire, culminating in major incursions into Anatolia led by his son Harun that compelled the Byzantines to pay a heavy annual tribute. His domestic policies also featured a reconciliation with various political factions and an official inquisition against heretics (zindiq). Al-Mahdi died under suspicious circumstances in August 785 in Masabadhan and was succeeded by his son, al-Hadi.