Akkadian hegemony over southern Mesopotamia lasts only two hundred years, despite their military prowess.

Sargon 's great-grandson is overthrown by the Guti, a mountain people from the east.

The fall of the Akkadians and the subsequent reemergence of Sumer under the king of Ur, who defeats the Guti, ushers in the third phase of Sumerian history.

In this final phase, which is characterized by a synthesis of Sumerian and Akkadian cultures, the king of Ur establishes hegemony over much of Mesopotamia.

Sumerian supremacy, however, is on the wane.