What is the deffinition of sumer?

Sumer was an ancient civilization located in the southern part of Mesopotamia, primarily in what is now modern-day Iraq. It is considered one of the world's earliest urban cultures, flourishing around 4500 to 1900 BCE. Sumerians are known for their innovations in writing (cuneiform), governance, and architecture, as well as significant contributions to mathematics and astronomy. The civilization is characterized by city-states such as Ur, Uruk, and Eridu, each with its own ruler and deity.