COIN, silver, Abbasid Dirham, Haroun 8th century.

Diameter approx. 2.5 cm.
The Abbasid Caliph Al-Mahdi (Muhammad ibn Abd Allah al-Mahdi), the third caliph of the Abbasid Caliphate, died in the year 169 AH (Hijri).
Here are key points regarding Al-Mahdi and the year 169 AH (approx. 785/786 AD):
Year of death: He passed away in the year 169 after Hijra.
Reign: He reigned from 158 AH until his death in 169 AH.
Successor: After Al-Mahdi's death in 169 AH, his son, Al-Hadi, took over as caliph for a short period, before the famous Harun al-Rashid (the caliph of the "golden era") took over.
Rule: During his time, the caliphate experienced stability and prosperity. He expanded the infrastructure and was known for attempting to combat heresy and strengthen the orthodox Islamic faith.