When and why did the Sumerian writing emerge?

The Sumerian civilization, which arose in southern Mesopotamia between the Tigris and Euphrates rivers in the fifth millennium BC, is the oldest known civilization on the planet. Sumerian writing, belonging to one of the types of cuneiform writing, arose at the turn of the third millennium BC due to the development and complication of social and industrial relations in society, when the possibilities of verbal communication became insufficient. Samples of Sumerian writing have survived to this day in the form of small clay tablets with cuneiform signs.