Tahirid dynasty
Kawus was succeeded by his son Khaydar, who had assisted Ahmad ibn Abi Khalid in his campaign against Ushrusana. Khaydar, who is usually referred to in the sources simply as al-Afshin, decided to enter the service of the Abbasids and made his way to al-Ma'mun's court. There he embarked on a military career, and became a commander in the caliphal army. With Afshin came a number of his followers, a number of whom were fellow natives of Ushrusana. These men were integrated into the army and, serving under their prince, became known as the "Ushrusaniyya". However, Afshin later tried to gain control over all of Khurasan and Transoxiana from the Persian Tahirid dynasty. He even secretly supported Mazyar, the Karenid ruler of Tabaristan, who had rebelled against the Abbasids. The rebellion, however, was soon suppressed, and Afshin's ambitions were revealed by the Abbasids. Furthermore, Afshin was accused of being a Zoroastrian, and he was soon imprisoned and died. His successor is not known; however, the Afshin family continued to rule Ushrusana until 892, when the Samanid ruler Isma'il ibn Ahmad incorporated Ushrusana into his Empire and killed its ruler, Sayyar ibn 'Abdallah.