The Parthian empire has experienced several major invasions by Roman armies during the past two centuries. These have damaged the richest provinces of the empire, in Mesopotamia, with the main victims being the hitherto flourishing cities of the region. Their repeated destruction, together with an increasing emphasis on native styles in art and architecture, has greatly reduced the influence of Greek culture in Parthian-ruled lands.
The influence of the Iranian aristocracy can be seen at work here, as it can in the increasing political instability which has plagued the empire. The authority of the monarchy has been weakened by the factional struggles of over-mighty nobles, and has greatly reduced the effective power of the central government in the provinces. By this date the empire is in fact little more than a collection of semi-independent kingdoms owing loose allegiance to the Parthian king.