It was founded by Iranian king Khosrow I on the east bank of the Tigris in the vicinity of Ctesiphon, Sasanian Empire, that was populated by deported Roman prisoners-of-war.
The Roman Emperor Justin and his heir and Caesar Justinian had sent substantial resources to the city to rebuild it.
[3] Procopius has provided detailed information on the building of the city, though his primary source is pro-Sasanian.
According to al-Tabari and al-Tha'alibi, the city was built on the plan of the Syrian metropolis and Khosrow I did everything in his power to make the residents want to stay.
Later in the Abbasid period, Caliph Al-Mansur used the city, then known as al Rumiyyah as seat of government for a few months.