The middle Euphrates region is well documented throughout the 1st millennium B.C. From the beginning of the period, the situation in the lower Khabur and the middle Euphrates varied between autonomy and the recognition of Assyrian domination. At the same time a passageway and a border between the Assyrian and Babylonian influences, the region was one of the entry points of the Assyrians into Babylonia, the Assyrians being in a position to ensure their domination at the heart of the territory of their southern neighbours, thanks to their troops posted in the region. The middle Euphrates, and in particular the region of Suhu, was the main route for the penetration of Aramaean and then Arab populations into Mesopotamia. Today the classical and cuneiform sources allow a path to be suggested, that seems to have been fairly common for the two population groups. The development of the caravan trade, as early as the 7th century, placed Suhu at the heart of exchanges between Arabia and Mesopotamia on a north-south axis. From being a secondary route in the Neo-Assyrian period until the end of the Seleucid empire, the middle Euphrates became the main axis of penetration into the Parthian empire from the west, which was probably not only under pressure from the vassal states of Rome, but also as a result of the development of relations with Arabia. Thus it was a strategic region, as much from an economic as a political point of view, that the Romans and Sasanids struggled over beginning in the 3rd century A.D.