During this period we may suppose that the city of Ur enjoyed a similar measure of independence, which increased in proportion to the decline of Semitic authority in the north. Gudea's campaign against Anshan affords some indication of the capability of independent action, to which the southern cities gradually attained. It is not likely that such initiative on the part of Lagash was unaccompanied by a like activity within the neighbouring, and more powerful, state of Ur. In an earlier age the twin kingdoms of Ur and Erech had dominated southern Babylonia, and their rulers had established the kingdom of Sumer, which took an active part in opposing the advance of Semitic influence southwards. The subjection of Sumer by the Dynasty of Akkad put an end for a time to all thoughts of independence on the part of separate cities, although the expedition against Erech and Naksu, which occurred in the patesiate of Lugal-ushumgal, supports the tradition of a revolt of all the lands in the latter part of Sargon's reign. Ur would doubtless have been ready to lend assistance to such a movement, and we may imagine that she was not slow to take advantage of the gradual weakening of Akkad under her later rulers. At a time when Gudea was marching across the Elamite border, or sending unchecked for his supplies to the Mediterranean coast or the islands of the Persian Gulf, Ur was doubtless organizing her own forces, and may possibly have already made tentative efforts at forming a coalition of neighbouring states. She only needed an energetic leader, and this she found in Ur-Engur, who succeeded in uniting the scattered energies of Sumer and so paved the way for the more important victories of his son.