Patriarchal Province of Seleucia-Ctesiphon
The Patriarchal Province of Seleucia-Ctesiphon was an ecclesiastical province of the patriarch of the Church of the East, with a metropolitan see in Seleucia-Ctesiphon. It existed from the fifth to the thirteenth centuries. The province consisted of a number of dioceses in the region of Beth Aramaye, between Basra and Kirkuk, which were placed under the patriarch's direct supervision at the synod of Yahballaha I in 420. Not to be confused with the Catholicate of Tigris (or Maphrianate of Tagrit), also known as the Catholicate of the East was established in 628–629 AD as the ecclesiastical headquarters for the Syriac Orthodox Church (Jacobite) within the Persian Empire to counter the Nestorian Catholicate, separate from the Church of the East. Centered in Tagrit (modern-day Iraq) on the Tigris River, the Maphrian held the second-highest rank after the Patriarch of Antioch, ruling until the seat moved to Mosul.