Note 209 — Chapter XIII · Decline of the Caliphs’ Authority in Khorāsān. The Tāhirides

Ma´mūn had conceived an aversion for Tāhir (some authors say because Tāhir reminded him of his brother Amīn’s death), and, being conscious of this, Tāhir naturally feared the proximity of the Caliph. He superseded a certain Ghassān, whom Ma´mūn had left in charge of Khorāsān.