The importance of control of the valleys of the Habur and Euphrates rivers to the Assyrians can hardly be over-estimated. The two river valleys are major routes from N. Syria and S.E. Turkey to southern Assyria and to Babylonia.
In the Neo-Assyrian period, control of the valley of the River Habur was won early, as the Assyrian armies marched westwards across N. Mesopotamia. Control of the Euphrates, between the confluence of the Habur and the Babylonian border, followed soon after.
We are particularly well-informed about the geography of the Habur and the Euphrates, below the confluence with the Habur, during the reigns of Adad-nerari II, Tukulti-Ninurta II and Aššurnaṣirpal II. Texts from the reigns of these three kings describe campaigns along the banks of these rivers and list each night's halting-place. These are usually described as “itineraries”. (Such texts are exceptionally rare from ancient Mesopotamia. Besides these three passages in the Assyrian annals, only two other lengthy, well-preserved itineraries in cuneiform have come down to us.) 2 Other, conventional passages from the Annals of Aššurnaṣirpal II are a valuable supplement to these texts.