The Sassanid Dynasty was established by Ardashir I (226241), a descendant of a line of the priests of goddess Anahita in Istakhr, Persis (Pars) who at the beginning of the third century had acquired the governorship of Persis. His father Papag (also pronounced Papak and Babak), was originally the ruler of a small town called Kheir, but had managed, in 205, to depose Gocihr, the last king of the Bazrangids (the local rulers of Persis as a client of the Arsacids) and appointed himself as the new ruler. His mother, Rodhagh, was the daughter of the provincial governor of Peris. The eponymous founder of the line was Ardashir I's paternal grandfather, Sassan, the great priest of the Temple of Anahita.
Pabag's efforts in gaining local power at the time escaped the attention of Artabanus IV, the Arsacid Emperor of the time who was involved in a dynastic struggle with his brother Vologases (Walakhsh) VI in Mesopotamia. Using the relief offered by these problems among the Arsacids, Pabag and his eldest son Shapur managed to expand their power over all of Persis. The subsequent events are unclear, due to the sketchy nature of the sources. It is however certain that following the death of Pabag around 220, Ardashir who at the time was the governor of Darabgird, got involved in a power struggle of his own with his elder brother Shahpur. The sources tell us that in 222, Shapur, leaving for a meeting with his brother, was killed when the roof of a building collapsed on him.[9]
At this point, Ardashir moved his capital further to the south of Persis and founded a capital at Ardashir-Khwarrah (formerly Gur, modern day Firouzabad). The city, well supported by high mountains and easily defendable through narrow passes, became the center of Ardashir's efforts to gain more power. The city was surrounded by a high, circular wall, probably copied from that of Darabgird, and on the north-side included a large palace, remains of which still survive.
After establishing his rule over Persis, Ardashir I rapidly extended his territory, demanding fealty from the local princes of Fars, and gaining control over the neighboring provinces of Kerman, Isfahan, Susiana, and Mesene. This expansion quickly came to the attention of Artabanus IV (216224), Ardashir I's overlord. Artabanus IV initially ordered the governor of Khuzestan to march against Ardashir in 224, but this ended up in a major victory for Ardashir. Artabanus himself marched a second time against Ardashir I in 224. Their armies clashed at Hormizdeghan, where Artabanus IV was killed. Ardashir I went on to invade the western provinces of the now defunct Parthian (Arsacid) Empire. Crowned in 226 at Ctesiphon as the sole ruler of Persia, he took 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 400-year-old Parthian Empire to an end and beginning four centuries of Sassanid rule.
Over the next few years, following local rebellions around the empire, Ardashir I further expanded his new empire to the east and northwest, conquering the provinces of Sistan, Gorgan, Khorasan, Margiana (in modern Turkmenistan), Balkh, and Chorasmia. He also added Bahrain and Mosul to Sassanid possessions. Later Sasanid inscriptions also claim the submission of the Kings of Kushan, Turan, and Mekran to Ardashir, although based on numismatic evidence, it is more likely that these actually submitted to Ardashir's son, the future Shapur I. In the west, assaults against Hatra, Armenia, and Adiabene met with less success.
