Birtha (Mesopotamia) Birtha (Mesopotamia) Birtha () was an ancient fortress on the river Tigris, which was said to have been built by Alexander the Great. It would seem, from the description of Ammianus, to have resembled a modern fortification, flanked by bastions, and with its approaches defended by out-works. Shapur II here closed his campaign in 360, and was compelled to retire with considerable loss. D'Anville and Edward Gibbon both identify Birtha as modern-day Tikrit, Iraq. The word "Birtha" in Syriac means a castle or fortress, and might be applied to many places. From the known position of Dura, it has been
Mesopotamia (Roman province) full province. Next Severus embarked on a war against Parthia, which he concluded successfully with the sack of the Parthian capital Ctesiphon. In emulation of Trajan, he re-established a province of Mesopotamia in 198, with Nisibis, elevated to the status of a full "colonia", as its capital. Unlike Trajan's province, which encompassed the whole of Roman-occupied Mesopotamia between the Euphrates and Tigris rivers, the new province was limited between the province of Osroene to the south, the Euphrates and Tigris to the north, and the river Chaboras (modern Khabur) to the east. For the remainder of its existence, the new