The dynasty itself traced its descent back to Bav, who was alleged to be a grandson of the Sasanian prince Kawus, brother of Khosrow I,[1] and son of the shah Kavad I (ruled 488–531), who supposedly fled to Tabaristan from the Muslim conquest of Persia.

[2][4] Parvaneh Pourshariati, in her re-examination of late Sasanian history, asserts that this Bav is a conflation of several members of the powerful House of Ispahbudhan: Bawi, his grandson Vistahm and his great-nephew Farrukhzad.

[5] She also reconstructs the events of the middle 7th century as a civil war between two rival clans, the Ispahbudhan and Valash's House of Karen, before the Dabuyid Farrukhan the Great conquered Tabaristan and subdued the various local leaders to vassalage.

[7] Sharwin I, along with the Karenid ruler Vandad Hormozd, led the native resistance to Muslim rule and the efforts at Islamization and settlement begun by the Abbasid governor, Khalid ibn Barmak (768–772).

Following his departure, the native princes destroyed the towns he had built in the highlands, and although in 781 they affirmed loyalty to the Caliphate, in 782 they launched a general anti-Muslim revolt that was not suppressed until 785, when Sa'id al-Harashi led 40,000 troops into the region.

His growing power brought him into conflict with the Muslim settlers at Amul, but he was able to take the city and receive acknowledgement of his rule over all of Tabaristan from the caliphal court.

One of their greatest kings, Shah Ghazi Rustam, is reported to have seriously defeated the Ismailis who were gaining prominence in Tabaristan and to have made significant progress in consolidating power in the Caspian provinces.

When these congratulations were finished, on the eight day the ispahad ascended the throne, girded on the royal girdle, and confirmed the governors in their appointments, and caused the ispahbads and amirs to cast aside their mourning, and clad them in robes of honour.