according to yaqubi, during the reign of the third abbasid caliph al-mahdi (775-85), afshin of oshrusana was mentioned among several iranian and turkish rulers of transoxania and the central asian steppes who submitted nominally to him. but it was not until harun al-rashid's reign in 794-95 that al-fadl ibn yahya al-barmaki led an expedition into transoxania and received the submission of afshin kharākana, the ruling akin. further expeditions were sent to oshrusana by al-ma'mun when he was governor in merv and later after he had become caliph. kawus ibn kharakhuruh, the son of the afshin karākana, withdrew his allegiance from the arabs. however, shortly after ma'mun arrived in baghdad from the east (817-18 or 819-20), a power struggle and dissension broke out among the reigning family of oshrusana.