The possession of Mesopotamia was a signal triumph for Babylonia.  As was inevitable, however, it brought Nebuchadrezzar into conflict some years later with the Assyrian king, Ashur-resh-ishi I, grandson of Ashur-dan, and father of the famous Tiglath-pileser I. The northern monarch had engaged himself in subduing the Lullume and Akhlami hill tribes in the south-east, whose territory had been conquered by Nebuchadrezzar.  Thereafter he crossed the Babylonian frontier.  Nebuchadrezzar drove him back and then laid siege to the border fortress of Zanki, but the Assyrian king conducted a sudden and successful reconnaissance in force which rendered perilous the position of the attacking force.  By setting fire to his siege train the Babylonian war lord was able, however, to retreat in good order.

Some time later Nebuchadrezzar dispatched another army northward, but it suffered a serious defeat, and its general, Karashtu, fell into the hands of the enemy.

Nebuchadrezzar reigned less than twenty years, and appears to have secured the allegiance of the nobility by restoring the feudal system which had been abolished by the Kassites.  He boasted that he was “the sun of his country, who restored ancient landmarks and boundaries”, and promoted the worship of Ishtar, the ancient goddess of the people.  By restoring the image of Merodach he secured the support of Babylon, to which city he transferred his Court.

Nebuchadrezzar was succeeded by his son Ellil-nadin-apil, who reigned a few years; but little or nothing is known regarding him.  His grandson, Marduk-nadin-akhe, came into conflict with Tiglath-pileser I of Assyria, and suffered serious reverses, from the effects of which his country did not recover for over a century.

Tiglath-pileser I, in one of his inscriptions, recorded significantly:  “The feet of the enemy I kept from my country”.  When he came to the throne, northern Assyria was menaced by the Muski and their allies, the Hittites and the Shubari of old Mitanni.  The Kashiari hill tribes to the north of Nineveh, whom Shalmaneser I subdued, had half a century before thrown off the yoke of Assyria, and their kings were apparently vassals of the Muski.

Tiglath-pileser first invaded Mitanni, where he routed a combined force of Shubari hillmen and Hittites.  Thereafter a great army of the Muski and their allies pressed southward with purpose to deal a shattering blow against the Assyrian power.  The very existence of Assyria as a separate power was threatened by this movement.  Tiglath-pileser, however, was equal to the occasion.  He surprised the invaders among the Kashiari mountains and inflicted a crushing defeat, slaying about 14,000 and capturing 6000 prisoners, who were transported to Asshur.  In fact, he wiped the invading army out of existence and possessed himself of all its baggage.  Thereafter he captured several cities, and extended his empire beyond the Kashiari hills and into the heart of Mitanni.