Abbasid Caliphate, al-Mahdi, AR Dirham - Madinat al-Salam Mint, AH 163

Al-Mahdi was the third Abbasid caliph, ruling from 775 to 785 AD. The son and successor of al-Mansur, he governed from Baghdad and expanded the caliphate's administration and public works. His silver dirhams circulated over long distances, and examples have been found in Viking Age hoards.

The Abbasid Dynasty overthrew the Umayyads in 750 AD and established Baghdad as its capital in 762 AD. Under Abbasid rule, the city became a major centre of trade, science, literature, and scholarship during the Islamic Golden Age. Although their political power declined over time, the Abbasids retained the Caliphate in Baghdad until the Mongol conquest in 1258 AD. A later branch held a largely ceremonial Caliphate in Cairo until 1517 AD. Abbasid silver dirhams have been found in Viking Age treasure hoards, reflecting the long-distance movement of Islamic silver into northern Europe.