The province functioned as some kind of vassal kingdom, being mostly ruled by princes from different royal families, who bore the title of Padashwargarshah ("Shah of Padishkhwargar").

On Shapur I's inscription at the Ka'ba-ye Zartosht the province is called Parishwar, whilst Islamic sources refer the region as Tabaristan,[1] which derives from Middle Persian Tapurstān ().

In the 550s, Karin, a member of the House of Karen, received land to the south of Amol by Khosrow I, thus starting the Qarinvand dynasty.

The western portion of Padishkhwargar included Gilan and Daylam, which was populated by the Gilaks and Daylamites, who were most likely adherents of some form of Iranian paganism, while a minority of them were Zoroastrian and Christian.

The non-Iranian tribes of Amariacae and Dribices that lived from the range of Amol to Gurgan, had most likely been assimilated by the Iranians into a prevalent Mazandarani population.