Because somebody else beat them.
Sumer was conquered many times. in about 2800 B.C. King Gilgamesh rules the city of Uruk 2400 B.C. Sargon I of Akkad conquers Sumer. 2000 B.C. Sumerians conquered by Amorites, from Babylon 1600 B.C. Hammurabi conquers all of Sumer; records Codes of Hammurabi 1400 B.C. Assyrians establish an empire from the town of Assur into Mesopotamia
With other Sumerians
The Sumerians gave us food and writing.
Sumerians did not have any advance over the economy relative to their place and time. They were there to do their mission.
The Sumerians were conquered by the Assyrians and those were conquered by the Chaldean.
Because somebody else beat them.
That was Assyria.
Sargon was the leader of the Semites but conquered the Sumerians. Thus he is quite often held as the "leader" of the Sumerians.
The Sumerian people of southern Mesopotamia (now Iraq) ruled the land from about 4000 BC until about 2000 BC. The Akkadians eventually conquered the Sumerians.
The Assyrians were in Mesopotamia. They were eventually conquered by Media and Babylonia. Babylonia was the next civilization that settled in Mesopotamia. This group was then conquered by the Persians, who extended their empire all the way to Asia Minor, or what is now Turkey.
2000 BCE
sumerians
The Sumerians
The Sumerians developed a form of pictograph.
WHile the obvious answer is Sumerians the country was conquered and over taken several times so the conquerors, such as the Akkadians, would be the inhabitants. Presently the inhabitants ar Iraqis.
The Sumerians