How did the sumerians city-state lose power

In their warfare between each other to acquite and protect theirland an water, some cities became dominant and established controlover lesser cities, establishing first concederations, thenempires, the first of which was Akkad uner Sargon, who establishedan empire in the later 3rd Millennium BCEcovering Mesopotamia, theLevant and part of today’s Iran. The cities lost independence underthis rule.