Reviewing an array of literary evidence as contained in universal and local histories, geographers works as well as Islamic, instructional and official chancellery treatises, in classical Arabic, Persian and foreign sources, and the Shahnama of Ferdowsi, in order to understand the nature of the socio-political, cultural, and religious institutions and values of Iranians throughout several thousand years, it has become clear to me that the division of Iranian history into the "Pre– and Post–Islamic" periods is not a sound terminology for studying it. My research into the nature of Iranian contributions to the world community in its socio-political, religious and artistic spheres indicates that, despite some political set backs, there has always been continuity in every one of the above. Considering current studies on conquest and conversion in Iran, furthermore, it has become clear to me that the above division of Iranian history is not commensurate with the ways in which classical historical sources in Arabic or Persian have understood these periods. Taking a long duree perspective, in this paper I will suggest that the most logical procedure for viewing Iranian history is to consider it as a spectrum that divides itself into the following periods: 1) The "Ancient Period," i.e. Iranian history in the prehistoric period; 2) the "Sovereignty Era" – i.e. the period of the Medes, the Achaemenids, the Parthians, and the Sasanians; 3) the "Post-Sasanian Period" – i.e. a period that witnessed the establishment of a multi-religious society; and finally 4) the "Islamic Period," a period which itself may be partitioned into the "Islamic Period without Iranian Sovereignty" – i. e. the 11th to the 15th centuries – and "Islamic Period with Iranian Sovereignty" – i.e. the 16th century to the present.