We have already seen how, during the early ages of her history, Assyria had been merely a subject province of the Babylonian empire. Her rulers had been viceroys owing allegiance to their overlords in Babylon, under whose orders they administered the country, while garrisons of Babylonian soldiers, and troops commanded by Babylonian officers, served to keep the country in a state of subjection. Gradually, however, the country began to feel her feet and long for independence. The conquest of Babylon by the kings of the Country of the Sea afforded her the opportunity of throwing off the Babylonian yoke. In the fifteenth century the Assyrian kings were powerful enough to have independent relations with the kings of Egypt, and, during the two centuries which preceded Tukulti-Mnib’s reign.
Assyria’s relations with Babylon were the cause of constant friction due to the northern kingdom’s growth in power and influence. The frontier between the two countries was constantly in dispute, and, though sometimes rectified by treaty, the claims of Assyria often led to war between the two countries. The general result of these conflicts was that Assyria gradually extended her authority farther southwards, and encroached upon territory which had previously been Babylonian. The successes gained by Ashur-uballit, Bel-nirari, and Adad-nirari I against the contemporary Babylonian kings had all resulted in the cession of fresh territory to Assyria and in an increase of her international importance. Up to the time of Tukulti-Mnib no Assyrian king had actually seated himself upon the Babylonian throne. This feat was achieved by Tukulti-Mnib, and his reign thus marks an important step in the gradual advance of Assyria to the position which she later occupied as the predominant power in Western Asia.
Before undertaking his campaign against Babylon, Tukulti-Mnib secured himself against attack from other quarters, and his newly discovered memorial inscription supplies considerable information concerning the steps he took to achieve this object. In his inscription the king does not number his military expeditions, and, with the exception of the first one, he does not state the period of his reign in which they were undertaken. The results of his campaigns are summarized in four paragraphs of the text, and it is probable that they are not described in chronological order, but are arranged rather according to the geographical position of the districts which he invaded and subdued.