Cuneiform script. Diagram showing the development of pictographs into stylised Cuneiform characters. Cuneiform, the first written language, was invented by the Sumerians who inhabited Mesopotamia (now south-eastern Iraq) from the 4th to the 3rd millennium BC. It was written on clay tablets with a reed stylus. The language died with the civilisation upon the rise of Babylonia in the late 3rd millennium BC, but the writing system was adopted by the Babylonians, Assyrians and Persians.