This scholarly work on Iran- Afghan relations in historical perspective is to find out the reasons and causes for the fluctuated relations of both the countries, who historically remain important players in shaping the history and structuring the political, social and administrative spheres of the region. Iran, Known in history as Persia and Afghanistan are located in such territory, which always had important geographical and strategic position. Since long there has always competition between both the states for holding authorities on their own land and even to occupy the vast territory of Central Asia and more importantly to come towards the plane areas of India. Most of the time in the course of the history, the other regional and global powers had their role in maximizing the differences between both the neighboring states and supported one against the other. In such circumstances Iran in general and Afghanistan in particular could not pay proper attention for the structural, political and social developments of their respective countries. In the recent past specially after the Sour revolution of 1978 in Afghanistan, Iran along with the rest of the countries of the world put her share in fighting against the revolutionary Government of Afghanistan, which was followed by civil war in Afghanistan in the start of 1990s, which let the way open for establishing the Taliban Government in Afghanistan. During the Taliban government the relation between the Iran and Afghanistan became too worse, however, the tragic event of 9/11 somehow provided an opportunity to both Iran and Afghanistan to come close and to establish good relations by supporting each other. Iran since 9/11 had investment in Afghanistan in different fields and positively played her role in accomplishment of UN peace plane and Iran positively played her role in 8the development of Afghanistan despite of the opposition and objection by USA and other Western countries.