Textual evidence indicated the existence of a Semitic population in the upper reaches of Lower Mesopotamia. The texts in question contained personal names and words from a Semitic language, identified as Old Akkadian. However, the use of the term "Akkadian" before the emergence of the Akkadian Empire is problematic, and it has been proposed to refer to this Old Akkadian phase as being of the "Kish civilization" named after Kish (the seemingly most powerful city during the ED period) instead. Political and socioeconomic structures in these two regions also differed, although Sumerian influence is unparalleled during the Early Dynastic period.