The name of Iran tells the story of a long-standing civilization in this land and is of great historical importance to researchers in different fields of Iranology. This study inquiries into the roots of the name of Iran and the ethnic groups that resided there and called themselves Iranian. Following a descriptive-analytic method, this paper investigates the etymology and background of this name in the forms of airyānam, ērān, aryān, etc. in the sense of Aryan in ancient oriental works, Avesta, ancient Iranian and Mesopotamian inscriptions, and ancient works of Western historiographers and geographers. The findings of this study demonstrate that this name in the sense of the people living in this land and in its different forms changed over the centuries and millennia in the course of history until it was established as a single name in the form of Iran in the Sassanid period to cover all the regions within the political borderlines of this era.