Having selected Quhistan as one of the important centers of the Nazaris’ activity in Iran, the local Muhtashams of this province focused their efforts on increasingly expanding their spheres of influence in the region. One of the important centers that the Nazaris had in mind to expand was Nīmrūz province (Sistan). By occupying the fortresses in the passageways at the entrance of Sistan, they would put the rulers of that province under pressure. One of these fortresses was Shāhanshāh or Shāhāndizh. The strategic position of this fortress, which was located in the North passageway of entrance to Sistan, would pave the way more and more readily for the infiltration of the Nazaris in Sistan; therefore, during their presence in the fortress, they created much tension with the local rulers of
Sistan.
Eventually, the coalition of the Sistan’s ruler of the time with the Mongol invaders enforced a different future for the residents of Shāhanshāh. The weakening of the Nazaris’ governance in Sistan was the ultimate aftermath of this coalition. The present writing, while introducing the Shāhanshāh fortress, seeks to examine and evaluate its role in the spread of Nazaris’ religious mission.