Mezue ahịrịokwu na-esonụ: Mgbe ọnwụ Harun na Khurasan na mbido 809, Abdallah nọgidere na mpaghara ahụ, sonye na ụlọ ikpe nke onye nketa nke abụọ nke Harun, al-Ma'mun (r. 813-833), na Marw. N'ime
Agha obodo na-esote n'etiti al-Ma'mun na nwanne ya nwoke, Caliph al-Amin (r. 809<unk>813), ọ nọgidere n'akụkụ na Marw. Ọ bụ otu n'ime ọtụtụ ndị isi ndị agha jụrụ iduzi gọọmentị al-Ma'mun, post nke mechara daa n'aka Fadl ibn Sahl. Mmekọrịta ya na al-Ma'mun adịghị mma, mana o so ya gaa n'ebe ọdịda anyanwụ ma soro ya mgbe ọ banyere Baghdad na 819.