Incidentally, these references afford striking proof of the wealth Babylon had now acquired, due no doubt to her increased commercial activities. Elam on the one side and Syria on the other[14] had furnished her with imports of precious stone, metal, and wood; and her craftsmen had learnt much from foreign teachers. In spite of the contraction of Hammurabi's empire, the life of the people in both the town and country districts of Akkad was not materially altered. The organized supervision of all departments of national activity, pastoral, agricultural and commercial, which the nation owed in great measure to Hammurabi, was continued under these later kings; and some of the royal letters that have been recovered show that orders on comparatively unimportant matters continued to be issued in the king's name. We know, too, of a good many public works carried out by Ammi-ditana, Abi-eshu's son. He cut only one canal, and he built fortresses for the protection of others, and named them alter himself. Thus, in addition to the Ammi-ditana Canal, we learn of a Dûr-Ammi-ditana, which he erected on the Zilakum Canal, and another fortress of the same name on the Mê-Enlil Canal. He strengthened the wall of Ishkun-Marduk, which was also on the Zilakum, and built Mashkan-Ammi-ditana and the wall of Kâr-Shamash, both on the bank of the Euphrates.[15] 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.