After the conquest of the Euphrates and Tigris provinces it was imperative that the royal residence should be fixed there.
Struck the Tigris some four marches above the site of Nineveh.
At Feluja, in the latitude of Bagdad, the Euphrates and Tigris closely approach each other, and then, widening out, enclose the plain of Babylonia (Arab.
At Bagdad the Tigris and Euphrates are less than 35 m.
But not to speak of the passage through the whole length of the Mediterranean, and another passage up the Persian Gulf and Red Sea, such a supposition would involve the complete circumnavigation of all Africa in three days, not to speak of the Tigris waters, near the site of Nineveh, being too shallow for any whale to swim in.
Julian pressed forward to Ctesiphon but succumbed to a wound; and his successor Jovian soon found himself in such straits, that he could only extricate himself and his army by a disgraceful peace at the close of 363, which ceded the possessions on the Tigris and the great fortress of Nisibis, and pledged Rome to abandon Armenia and her Arsacid protg, Arsaces III., to the Persian.
While the Tigris never played the same role historically as the Euphrates, numerous remains of antiquity are to be seen along its course.
If, as most critics agree, it is a historical romance (cf., e.g., the book of Judith), it is possible that a writer, preferably one who lived in the post-exilic age and was acquainted with Babylonian history, desired to enhance the greatness of Abraham by exhibiting his military success against the monarchs of the Tigris and Euphrates, the high esteem he enjoyed in Palestine and his lofty character as displayed in his interview with Melchizedek.
The site of Nisibis, on the great road between the Tigris and the Mediterranean, and commanding alike the mountain country to the north and the then fertile plain to the south, gave it an importance which began during the Assyrian period and continued under the Seleucid empire.
While the history of the great area between the Nile and the Tigris irresistibly emphasizes the insignificance of Palestine, this land's achievements for humanity grow the more remarkable as research tells more of its environment.