Vologases VI

Vologases VI (Parthian: Walagash, Persian: بلاش, Balāsh) was the uncontested king of the Parthian Empire from 208 to 213, but afterwards fell into a dynastic struggle with his brother Artabanus IV, who by 216 was in control of most of the empire, even being acknowledged as the supreme ruler by the Roman Empire. Vologases VI continued to rule Seleucia until 221/2, and coin mints of him even appear in Mesopotamia until 228, when he was presumably defeated by the Sasanian Empire, who had previously defeated Artabanus IV and now succeeded the Parthians as the kings of Iran.

Source: Wikipedia — https://en.wikipedia.org/wiki/Vologases_VI