The political culture of Iran in medieval centuries, has considered the blood lineage with ancient Iran and Its mythical – historical figures as one of the basic conditions and requirements for legitimacy, power and most importantly, those elements’ continuity. On the other hand, the lacks of blood lineage with ancient Iran were considered as serious threat and deficiency for each government. Thus a part of concerns and mentality power and special dedications of rulers and their scholars were devoted to the implication of the policy of construction of fake genealogy and its propaganda. However their efforts were faced with serious doubts, but the persistence of this issue in all those centuries and the diligently pursuance of that policy, reflects the effectiveness and influence of those efforts on the public opinion of that era. In this regard, some basic questions could be raised such as the question about the reasons which actuated the governments to construct fake genealogy in those periods and why the mythical and historical figures were introduced as the reference ancestries. The results of the research show that the governments of that era have chosen the policy of genealogy construction in the light of the historical vision of Iranian society as their priority to legitimate their rule and to deal with contempts and to balance with the other competitors.