When and why did the Sumerian state arise?

The first state that arose on the territory of Mesopotamia was the ancient Sumer 4-2 thousand years BC. In the period from the 28th to the 27th century BC. the main city of the Sumerian state was Kish, this time is considered to be the period of the early Sumerian dynasty. Then, from the 27th century to the 26th century BC. the ruler of the city of Uruk Gilgamesh is freed from the hegemony of the city of Kish. Thus, a new dynasty begins to rule and the new cities of Lagash and Nippur flourish. In the second half of 3 thousand. Sumerians are captured by the Semitic tribes of Akkadians, therefore they occupy a dominant role in Mesopotamia.