The rise of Islam in the mid-7th century led to the collapse of the power equations in the world of that day. The new Muslim Arabs defeated the most important world powers in a marvelous military movement. They drew the great Sassanian Empire to a collapse and reached the political capital and religious center of the Roman Empire. The main problem the present article addresses is what made it possible for the Muslim Arabs to achieve such quick and stunning victories? Undoubtedly, in these miraculous victories, irrespective of the spiritual power of Islam materialized in the form of jihad and martyrdom-seeking, Muslims must also have been materially and militarily attained to a degree of strength in order to fulfill their religious or material aims. In this paper, the military power of the Arab Muslims was examined from two aspects of the Arabs' military differences with Iranians and Romans and the new military tactics of the Arabs, adopted proportionate to the military genius of their commanders. It was found that agility, diligence, personal ingenuity, and the difference in the method of Arabs' fighting on the one hand and the design of combat techniques, combining the Iranian and Roman methods of warfare with those of Arabs led to Arabs' overthrowing Iran and Rome.

An investigation of the Fotouh news indicates that the commanders of the Arab Muslim Corps in most cases preferred to gain control over the land of Iran through the conclusion of peaceful agreements instead of war. For this reason, in different ways, they gave immunity to the Iranian nobles and their subjects, despite having a history of war and even violation of the treaty and rebellion. They sat at the negotiating table with them. Considering the repetition of this policy, this question is raised, "what were the motivations in persuading the Arab political-military elites to adopt a strategy of reconciliation and compromise with the Iranian elites? " Although the great event of conquest of Iran by the Muslim Arabs has been discussed and analyzed by the historians from various angles, no comprehensive and independent research has been done to answer the question. Relying on the first-hand sources and using a historical approach and an analytical-descriptive method, the author tries to answer this question. The findings show that factors such as facilitating the advances of the Arab armies in Iran with the assistance of the local rulers, reducing resistances and protests in different areas of Iran by using the ethnic influence and prestige of the big local families, using the military force of the Iranian elites in the internal conflicts of Arab tribes, and using the knowledge and experiences of the Iranian bureaucrats and peasants in governing the occupied areas have been effective in concluding peaceful contracts. It was also the reason for the Arab political-military elites’ inclination to adopt the strategy of reconciliation and compromise with the Iranian nobles in conquering the land of Iran.

The conquest of Iran by Muslim Arabs is one of the most important events in Iranian history that led to major developments and dramatic changes in the fate and future of this land. Accordingly, such an event has been repeatedly studied by scholars from various perspectives. Among the many issues and events that have followed this great and influential event for the history of this land that each of them are of significant research importance, this article, based on the religious assumption, examines the aims of the Muslim Arabs invasion of Iran and also the legitimacy or illegitimacy of this invasion. However, most scholars based on narratives of the conquest of Muslim historians believe that the Arab invasion of Iran had a sacred purpose in promoting and spreading of Islam and rescuing the oppressed people of Sassanid rule, but this essay attempts to point out such views from a historical perspective by critically examining historical sources and comparing how the Arab invasion of Iran with the Prophet's military tradition and Jihadic commandments in the Quran.

The conquest of Iran by the Muslim Arabs that marked the fall of the Sassanid dynasty, as well as the questions about its justifications and consequences, have been extensively discussed by historians from a variety of angles. Hence, there are divergent views on the rationales underlying their rapid and unpredictable domination over the great Sassanid territory. For example, references have been made to the reconciliation of some Iranian aristocratic and ruling families with the Arabs for economic and religious purposes. However, no independent and systematic research has explored the non-economic and non-religious goals and motives of the Iranian aristocracy in reconciliation with the Arabs so far. This study, utilizing a descriptive-analytical method, strives to explore the political, social, military, and security stimuli of the Arab conquerors. According to findings, the urgency to protect one’ s life, maintain former positions, promote one’ s socio-political status in the new ruling system, exploit Arab military force to get rid of traditional rivals, and be realistic about surviving the military crisis and regaining power impelled a class of Iranian aristocrats to pursue the strategy of reconciliation with the Arab invading forces.

A research into “the predictive literature” and its role in the victory of Muslim Arabs over the ancient Persians clearly reveals the mental or moral character of the Persians in the times of military conflicts and make it easier for us to analyze the crushing defeat of the Sassanid Empire by the assailing Muslims. Curious enough to know more about the future of their rule, the ancient kings were deeply interested in the prophecy and prediction of events based on astronomy and interpretation of dreams. For this very reason, they were attaching much importance to the statements of priests and soothsayers and believed in their prognostications. A review of the historical documents and resources proves that the predictive literature played a key role in the culmination or collapse of the Sassanid empire. This, however, does not minimize the importance of other factors behind the foundation or collapse of this great Empire. Indeed, “the belief in failure” grew in the minds of the Persians in the early years of the advent of Islam. The prediction by Prophet Mohammad (PBUH) of the failure of great empires of Persia and Rome contributed immensely to other conquests by the Muslim Arabs.

The invasion at Iran by the Arabs, as a great event with deep implications, has contributed to shaping the new history of Iran. The majority of Iranians gradually embraced Islam, but the unIslamic and cruel behaivour of the Umayyads, the Abbasids and the Arab aristocrats caused to Iranians react. At first, it was an intellectual and cultural reaction, and the revival of Iranian identity and Persian language and literature were the distinct sign of it. It was in the third century A.H. that the Iranian dynasties came to power and political independence was attained.The present article, based on the events of the First and Second centuries A.H., is to study the reaction of Iranians to Arabs.

The arrival of the Arabs on the Sassanidʼ s regality was confronted with the reaction of various groups of Iranian society. One of Iran's major minorities was Christians, who had a particular confrontation with the Arab conquerors. These reactions, which were often interactive and contradictory, occurred in different parts of Sassanid Iran. The interaction of Christians in the western regions of Iran and Iraq was due to their ethnicity and Arabic language and rivalry with the Christians in the inner regions of Iran. But the approach of Christians in the inner regions of Iran due to the existence of ethnic and linguistic differences with the conquerors, were often supported by Muslim protesters such as Khawarij to confront and oppose Arab conquerors. This article explains how Christians of Iran reacted to the arrival of Muslim conquerors in the first century AH.

The migration of Arab tribes to Khuzestan, which started at the same time as the Islamic conquests, led to a new chapter in the political, social and economic situation of this land. Arabs entered Khuzestan with different motivations and settled in its rural and urban areas and finally managed to take control of the affairs and establish their sovereignty in the region. Sepahs, peasants and farmers were among the most effective social classes in the political, social and economic developments of Khuzestan in the Sassanid era and the beginning of the Islamic era. The Sassanid Army was one of the upper classes of the society and one of the important pillars of the government. After successive defeats and the death of its commanders, it inevitably put down the shield of resistance and surrendered to the Army of Islam. Peasants were one of the most important aristocratic families of the late Sassanid era, who showed different reactions to the Arab invaders when the Muslim Arabs invaded. Some of them were captured or killed, but many cooperated with Muslims to maintain their position. Some remained in their previous position by paying jizya and some by converting to Islam. Farmers, who were among the subjects of the peasants, and their lives were always through the peasants who were the lords of the land.

The killing of Yazdgerd, the last Sasanid king in the years 31 in northeast Iran by an unknown miller, is one of the most important events in the Iran`s history. By the murder of this king Sasanid`s political life was terminated and Iran`s status was changed socially, economically and culturally. In spite of the end of Sasanid government, civilization elements of that government like old tax regulations were transmitted to Islamic era. There has not been any independent study about the transmission and the quality of influence of these regulations yet. This article wants to answer this question using both a descriptive-analytic method and also an information collection one that in which contexts Sasanid`s tax regulations had been transmitted and what effects they had in tax context in primary Islamic centuries? Findings of this study show that Sasanid`s tax regulations like Mukasama, Ushur, Massahi and Jizya had been used in primary Islamic centuries and they had been transmitted in financial, geographical and cultural contexts.

The conquest of Iran by Muslim Arabs is one of the most important developments in Iran's history. Iran was completely conquered over two decades and the Sassanid government collapsed. There are still a lot of questions about this fall and its reasons. This article, which is based on the main resources of conquest of Iran, tries to present a new model for analyzing the course of the conquests. The main question of the study thus is if the conquests followed a particular pattern and if they can be presented in the form of a single theory. The second question concerns how the cities were conquered. Were they conquered through war or peacefully? In response to the above question, the hypothesis of this paper is formed. Iran was divided into eight regions, at the borders of which, one can see the greatest resistance of the Iranian military, which we call "border-threshold resistance". Once the borders were broken, the advance of Muslim Arabs was faster and with less fighting. As a result, the clashes are mostly generated by the military, and the general public are less involved at war. Understanding the speed and the quality of the Arab conquests of Iran is subject to understanding this pattern.