|Biographical detail : || The 8th Abbaside caliph and the fourth son of Harun-al-Rashid.
He built a new capital for himself called Samira. He was a Matazalite. He was the first caliph to add the title of Billah to his name.
The figure "8" was of great importance in his life. He reigned 8 years, was the 8th Caliph, ascended the throne on the 18th to 218 A.H., lived 48 years, fought 8 battles, built 8 palaces, had 8 sons and 8 daughters also died on the 18th.