When did the Sasanian Empire rise?

Ardashir was aided by the geography of the province of Fars, which was separated from the rest of Iran. Crowned in 224 at Ctesiphon as the sole ruler of Persia, Ardashir took the title shahanshah, or "King of Kings" (the inscriptions mention Adhur-Anahid as his Banbishnan banbishn, "Queen of Queens", but her relationship with Ardashir has not been fully established), bringing the 400-year-old Parthian Empire to an end, and beginning four centuries of Sassanid rule.