 Tahir and Ya'qub returned to Sistan, reaching Zarang in May of that year.From the onset of his reign, Tahir and his brother were under the thumb of the Turkish slave commander Sebük-eri, who managed to destroy Tahir’s vizier and replace him with one more to his liking.Tahir spent much of his time early in his reign in the western part of his territories, having to deal with the occupation of Fars by the Abbasid Caliph al-Mu'tadid after the downfall of 'Amr.