The battle was the culmination of rivalry between Ardashir son of Papag, Parthian vassal king of Persis and his overlord, Shahanshah Artabanus IV of Parthia. Ardashir ascended the throne of Persis in 208 AD after deposing his elder brother, Shapur. He immediately started expanding his domains and quickly conquered neighboring provinces of Kerman, Isfahan, Susiana (modern Khuzestan), and Mesene (modern Maysan). This expansion brought the attention of the Arscacid Great King Artabanus IV (216–224 AD).