Under Khammurabi a Samsi-Hadad (or Samsi-Raman) seems to have been vassal-prince at Assur, and the names of several of the high-priests of Assur who succeeded him have been made known to us by the recent German excavations. The foundation of the monarchy was ascribed to Zulilu, who is described as living after Bel-kapkapi or Belkabi (1900 B.C.), the ancestor of Shalmaneser I. Assyria grew in power at the expense of Babylonia, and a time came when the Kassite king of Babylonia was glad to marry the daughter of Assur-yuballidh of Assyria, whose letters to Amenophis (Amon-hotep) IV. of Egypt have been found at Tell el-Amarna. The marriage, however, led to disastrous results, as the Kassite faction at court murdered the king and placed a pretender on the throne. Assur-yuballidh promptly marched into Babylonia and avenged his son-in-law, making Burna-buryas of the royal line king in his stead. Burna-buryas, who reigned 22 years, carried on a correspondence with Amenophis IV. of Egypt. Shalmaneser I. After his death, the Assyrians, who were still nominally the vassals of Babylonia, threw off all disguise, and Shalmaneser I. (1300 B.C.), the great-great-grandson of Assur-yuballidh, openly claimed the supremacy in western Asia. Shalmaneser was the founder of Calah, and his annals, which have recently been discovered at Assur, show how widely extended the Assyrian empire already was.
Campaign after campaign was carried on against the Hittites and the wild tribes of the north-west, and Assyrian colonists were settled in Cappadocia. His son Tukulti-In-aristi conquered Babylon, putting its king Bitilyasu to death, and thereby made Assyria the mistress of the oriental world. Assyria had taken the place of Babylonia.
For 7 years Tukulti-In-aristi ruled at Babylon with the old imperial title of "king of Sumer and Akkad." Then the Babylonians revolted. The Assyrian king was murdered by his son, Assur-nazir-pal I., and Hadad-nadin-akhi made king of Babylonia. But it was not until several years later, in the reign of the Assyrian king Tukulti-Assur, that a reconciliation was effected between the two rival kingdoms. The next Assyrian monarch, Bel-kudur-uzur, was the last of the old royal line. He seems to have been slain fighting against the Babylonians, who were still under the rule of Hadad-nadin-akhi, and a new dynasty was established at Assur by In-aristi-pileser, who claimed to be a descendant of the ancient prince Erba-Raman. Tiglath-pileser I. His fourth successor was Tiglath-pileser I., one of the great conquerors of Assyria, who carried his arms towards Armenia on the north and Cappadocia on the west; he hunted wild bulls in the Lebanon and was presented with a crocodile by the Egyptian king. In 1107 B.C., however, he sustained a temporary defeat at the hands of Merodach-nadin-akhi (Marduk-nadin-akhē) of Babylonia, where the Kassite dynasty had finally succumbed to Elamite attacks and a new line of kings was on the throne.
Of the immediate successors of Tiglath-pileser I. we know Assur-nazir-pal III. little, and it is with Assur-nazir-pal III. (883-858 B.C.) that our knowledge of Assyrian history begins once more to be fairly full. The empire of Assyria was again extended in all directions, and the palaces, temples and other buildings raised by him bear witness to a considerable development of wealth and art. Calah became the favourite residence of a monarch who was distinguished even among Assyrian conquerors for his revolting cruelties. Shalmaneser II. His son Shalmaneser II. had a long reign of 35 years, during which the Assyrian capital was converted into a sort of armed camp. Each year the Assyrian armies marched out of it to plunder and destroy. Babylon was occupied and the country reduced to vassalage. In the west the confederacy of Syrian princes headed by Benhadad of Damascus and including Ahab of Israel (see Jews, § 10) was shattered in 853 B.C., and twelve years later the forces of Hazael were annihilated and the ambassadors of Jehu of Samaria brought tribute to "the great king." The last few years of his life, however, were disturbed by the rebellion of his eldest son, which well-nigh proved fatal.
Assur, Arbela and other places joined the pretender, and the revolt was with difficulty put down by Samsi-Raman (or Samsi-Hadad), Shalmaneser's second son, who soon afterwards succeeded him (824 B.C.). In 804 B.C. Damascus was captured by his successor Hadad-nirari IV., to whom tribute was paid by Samaria.
With Nabu-nazir, the Nabonassar of classical writers, the so-called Nabu-nazir. Canon of Ptolemy begins. When he ascended the throne of Babylon in 747 B.C. Assyria was in the throes of a revolution. Civil war and pestilence were devastating the country, and its northern provinces had been wrested from it by Ararat. In 746 B.C. Calah joined the rebels, and on the 13th of Iyyar in the following year, Pulu or Pul, who took the name of Tiglath-pileser III., seized the crown and inaugurated a new and vigorous policy.