An examination of the data pertaining to the Šimaškian Yabrat (Ebarat) reveals that this Iranian ruler controlled, during the later phase of the Ur III period, a powerful state in central Iran. It appears that Yabrat's influence extended to the neighboring state of Anšan, which may even have been his political dependency. A close and dependent ally of the House of Ur until the reign of Ibbi-Suen, Yabrat subsequently became a major threat to Babylonia. The article seeks to reconstruct the history of the interactions between Yabrat and the Ur III state, and to provide an improved understanding of Šimaški as a political and geographic phenomenon. The question of the historicity of the so-called “Šimaš- kian King List” is also considered.