The region called Oshrusana, which lies to the south of the great, southernmost bend of the Syr Darya and extends roughly from Samarkand to Khujand, was inhabited by an Iranian population, ruled by its own princes who bore the traditional title of Afshin, at the time of the first Arab invasion of Transoxiana under Qutayba ibn Muslim (712-714).
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 bin Yahya al-Barmaki led an expedition into Transoxania and received the submission of the ruling Akin known as Kharākana.
This Karākana had never previously humbled himself before any other potentate.
Further expeditions were nevertheless sent to Oshrusana by Al-Ma'mun when he was governor in Merv and after he had become caliph.
Kavus, son of the Afshin Karākana who had submitted to Fadl bin Yahya, had withdrawn his allegiance from the Arabs; but shortly after Ma'mun arrived in Baghdad from the east (817-18 or 819-20), a power struggle and dissensions had broken out among the reigning family of Oshrusana.
According to most of the sources, al-Ma'mun's heir, Al-Mu'tasim, not only made Afshin governor of Azarbaijan and seconded high-ranking officers to serve under him, but also ordered exceptionally large salaries, expense allowances, and rations for him.
In 831-833, he had suppressed uprisings in Egypt from remote regions to Alexandria.
The news of his great success in taking Bima in Egypt, which had surrendered to Afshin's extension of al-Ma'mun's promise of safe conduct, had been proclaimed on June 2, 832.
Al-Mu'tasim had in 835 appointed Afshin as a governor of Azerbaijan to fight against Babak Khorramdin, leader of anti-Islamic neo-Mazdakite Persian movement of the Khurramites.
After a fierce resistance by Babak's army, Afshin eventually defeats it and captures Babak's castle of Bazz in August 837.
Ya'qubi (Tarikh II, 579) records Afshin freeing seventy-six hundred Arab prisoners from this fortress, and he destroys the castle.
The Khurramite leader escapes to take refuge in the mountains controlled by local Christian Armenian prince Sahl Smbatean.
