the rulers of the oshrusana or ustrushana (istarawshan) went by the title of "afshin", and the most famous of whom was khedār (arabicised "haydar") b. kāvūs. our early knowledge of the ruling family of oshrusana is derived from the accounts by the islamic historians (tabari, baladhuri, and ya'qubi) of the final subjugation of that region by the 'abbasid caliphs and the submission of its rulers to islam.