Ardashīr I (ca. 180-242) - By the early 3rd century, the Parthian Empire was rotting from the inside. For centuries it had managed to fend off its chief rival, the Roman Empire. While Rome succeeded in winning battles and taking some land, it never threatened Parthia's very survival. What did, however, was an emerging new dynasty from within its own boundaries. From the southern province of Fars, a new ruler, named Ardashīr (eventually the 1st) began conquering his neighbors and exerting influence over an expanding region. Eventually, he even toppled, Tiri, the satrap of Fars. But as long as he confined his conquests to his native province, the Parthian king, Artabanus V, ignored him (or at least pretended to). He didn't have much choice; his government was so weakened, victory in a conflict with Ardashīr was far from certain. However, in 224, Ardashir crossed his provincial border and attacked neighboring Khuzestan. This was a move Artabanus could not allow to go unanswered. He invaded Fars and engaged Ardashīr in a series of three conflicts, the final one being the Battle of Hormozdgān. Ardashir was ultimately victorious, and a feeble Parthian Empire was dead. Ardashīr established a new kingdom which became the Sāssānid (or Sāssānian) Empire (named for his grandfather Sāssān). His dynasty ruled for the empire's entire lifespan. Officially his reign lasted from 224 to 242. The primary source for events at this time is the Muslim historian Al-Tabari (840-923).