reasons for the continuity of the dabuyid rule in tabaristan

the dabuyids is a local dynasty who managed to dominate over an area known as padashwargar for more than a century. they came to power when on the one hand the sassanid empire was on the decline, and on the other hand the arab invasion had become irresistible. however, the dabuyids managed to take root in such circumstances and survive powerfully for a long time. the dabuyids even remained alive during the decline and fall of the great contemporary rules of sassanid empire and umayyad caliphate, without losing the essence of its local rule. it seems that they took the best advantage of their specific geographic location, as well as depending on military power and political relations and finally maintaining the ancient values and traditions and relying on their own local acceptance, in order to ensure their continuity and survival. the present study examines relevant sources about such causes and reasons.