in Ardashir's contest with Artabanus in the Battle of Hormozdgan on April 28, 224, Artabanus was killed by Ardashir and the Parthian dynasty was overthrown with his death. The year of the occurrence of the battle is confirmed by Shapur I's inscription in Bishapur. The extended report of the Battle of Hormozdgan is probably made for the Sasanian's formal history. If the mentioned assumption is right, the writing may have been the main source of Al-Tabari's History. After Artabanus's death, Ardashir's quest for extending his kingdom did not end. In a procedure, the large landlord Parthian houses, either submitted to Ardashir (willingly or unwillingly) or were conquered by him. The subsequent sources emphasized on the Sasanians' hatred of everything adapted from the Parthians. The existence of such a mentality in Ardashir is understandable; but even he was forced to establish his newborn government on Parthian foundations by the help of other remarkable Iranian houses, who were either affiliated with the Parthians or nursed by them. However, no change is seen in that hatred of the Parthians in the next generations of Sasanian emperors either. Therefore, it can be deduced that the Parthians enforced a more hard and tyrannical domination than presumed on their submitted shahs and that might have been the reason that facilitated Ardashir's conquest. After coronation There is controversy among specialists about the year of Ardashir's coronation; according to W.B. Henning's studies and calculations, Ardashir was crowned on April 28, 224; however, the calculations of H. Taqizadeh show the date April 6, 227. Josef Wiesehöfer believes the year of Ardashir's coronation in Ctesiphon 226 and at the time of his invasion on Northern Mesopotamia based on other sources. Anyway, by choosing the title Shahanshah (king of kings), Ardashir revealed his inclination toward government. During about 226–227, Ardashir experienced a failed attempt to conquer Hatra, which was previously unsuccessfully tried by Trajan and Septimius Severus, while on a crusade for taking the northwest regions of the land. In the late Parthian era, Hatra had become semi-dependent due to the gradual deterioration of the central government. After that unsuccessful attempt of Ardashir's in the west, he started taking eastern lands and dominating large Parthian landlords, local noblemen and large Iranian houses and was successful. The exact extent and limits of Ardashir's ruled domain can not be determined correctly. Ardashir's domain in the west was probably extended to the traditional borders