Vologases VI was driven out of Mesopotamia by Ardashir I's forces soon after 228.[12][2] The leading Parthian noble-families (known as the Seven Great Houses of Iran) continued to hold power in Iran, now with the Sasanians as their new overlords.[10][5] The early Sasanian army (spah) was identical to the Parthian one.[13] Indeed, the majority of the Sasanian cavalry composed of the very Parthian nobles that had once served the Arsacids.[13] This demonstrates that the Sasanians built up their empire thanks to the support of other Parthian houses, and has due to this has been called "the empire of the Persians and Parthians".[14] However, memories of the Arsacid Empire never completely vanished, with efforts trying to restore the empire in the late 6th-century made by the Parthian dynasts Bahram Chobin and Vistahm, which ultimately proved unsuccessful.[15][16]