Factors that aided the rise to supremacy of the Sassanids include the Artabanus-Vologases dynastic struggle for the Parthian throne, which had probably allowed Ardashir to consolidate his authority in the south with little or no interference from the Parthians; and the geography of the Fars province, which separate it from the rest of Iran.

Ardashir, crowned in 224 at Ctesiphon as the sole ruler of Persia, takes the title Shahanshah, or "King of Kings" (the inscriptions mention Adhur-Anahid as his "Queen of Queens", but her relationship with Ardashir is not established), bringing the four hundred year-year-old Parthian Empire to an end, and beginning four centuries of Sassanid rule.

Claiming Achaemenid descent and proclaiming a revival of ancient glory, he names his dynasty after his ancestor Sasan (believed to be his grandfather) and embraces Zoroastrianism.