The systematic fortification of the rivers and canals may perhaps be interpreted as marking an advance of the frontier southward, in consequence of which it was advisable to protect the crops and the water-supply of the districts thus recovered from the danger of sudden raids. On two occasions Ammi-ditana claims, in rather vague terms, to have freed his land from danger, once by restoring the might of Marduk, and later on by loosing the pressure from his land; and that, in his seventeenth year, he should have claimed to have conquered Arakhab, perhaps referred to as "the Sumerian,"[16] is an indication that the Sea-Country kings found ready assistance from the older population of the South. Moreover, of the later West-Semitic kings, Ammi-ditana alone appears to have made headway against the encroachments of the Sea-Country. The most conclusive proof of his advance is to be seen in the date-formula for his thirty-seventh year, which records that he destroyed the wall of Nîsin,[17] proving that he had penetrated to the south of Nippur. That Nippur itself was held by him for a time is more than probable, especially as one of his building-inscriptions, still unpublished, is said to have been found there[18]; and we know also, from a Neo-Babylonian copy of a similar text, that he claimed the title "King of Sumer and Akkad."[19] Under him, then, Babylon recovered a semblance of her former strength, but we may conjecture that the Sea-Country retained its hold on Larsa and the southern group of cities.
We are furnished with a third valuable synchronism between the dynasties of Babylon and of the south by the reference to Ammi-ditana's destruction of the wall of Nîsin, for the date-formula adds that this had been erected by the people of Damiḳ-ilishu. The ruler referred to is obviously the third king in the dynasty of the Sea-Country, who succeeded Itti-ili-nibi upon the throne.[20] We may conclude that it was in his reign, or shortly after it, that Ammi-ditana succeeded in recovering Nîsin, after having already annexed Nippur on his southward advance. In his thirty-fourth year, two years before the capture of Nîsin, he had dedicated an image of Samsu-iluna in the temple E-namtila, and we may perhaps connect this tribute to his grandfather with the fact that in his reign Babylon had last enjoyed the distinction conferred by the suzerainty of Nippur.