Sumerian ( "native tongue") is the language of ancient Sumer and a language isolate which was spoken in southern Mesopotamia (modern Iraq). During the 3rd millennium BC, a very intimate cultural symbiosis developed between the Sumerians and the Akkadians, which included widespread . The influence of Sumerian on Akkadian (and vice versa) is evident in all areas, from lexical borrowing on a substantial scale, to syntactic, morphological, and phonological convergence. This has prompted scholars to refer to Sumerian and Akkadian in the third millennium as a Sprachbund (area of linguistic convergence).