Shahdiz Fortress,  Leading the Passive Defense Principles of the Ismaili Period South Khorasan

Defending history has taken place as a factor and inactive. The defensive agent that is directly in front of the enemy and the defensive defense is a way to reduce the damage caused by wars in the cities and castles of different regions of Iran. Looking at the history of human civilization, it can be seen that the advent of early civilizations has been accompanied by war. South Khorasan (Qehistan) has been threatened by enemies because of its strategic location in the Middle East. It is necessary to pay attention to this issue and to pay attention to inactive defense policy and to identify its defense components. By studying and studying the Ismaili index in the southern Khorasan region, which can lead to the discovery of their sustainability code. And the pattern of them will lead to the creation of permanent buildings The result is not a single unit at the Ismaili-related level in this region (unity at the same plurality). This research, while defining the principles of inertial defense, examines how it is used in some South Khorasan tribes through descriptive-analytical method. The data collection tool of this research is based on library and field studies. The results of this research indicate the necessity of studying the use of inertial defense principles at the Ismaili-based index in the South Khorasan region.