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
Agriculture in ancient Mesopotamia east, rising from 200-500 m in altitude, and which are now known as Jazirah (from the Arabic, "al-jazayra", 'the island'). Thus, the rivers flow through valleys which are 1-10 km wide. The southern half of Mesopotamia, which is the part properly called Mesopotamia from a geophysical point of view, since it is where the Tigris and Euphrates flow close to one another, is a vast plain, which is 150-200 km wide and has only a very slight incline, decreasing to the south until it is nearly non-existent. This encourages the development of river braiding, sudden changes of course, and the