Harthama b. Aʿyan (d. 200-1/816-7) was an important political and military figure who assisted in the enthronement of the ʿAbbāsid caliphs al-Rashīd and al-Maʾmūn. His background is murky. He was from Khurāsān but belonged to the Banū Ḍabba (a famous tribe originally centred in al-Yamāma, in the central Arabian Peninsula), so his family were probably immigrants from the west. To complicate matters, he is described as mawlā amīr al-muʾminīn , an ambiguous term indicating some form of client/patron relationship to the ruling family.