Owing to various reasons including the existence of contradictions and myths in the historical records concerning the conditions of Iran during the period that immediately preceded the conquest of Iran – which had for the most part been written with the aim of catering to communal pride – the religious conditions of Iran at the time of the advent of Islam are shrouded in ambiguity. Since the conquest of Iran had taken place during different phases of the caliphate, apparently with the motive of extending the invitation to Islam, the available records should have included elements clearly depicting the assimilations activities. However, these records rarely make any worthwhile mention, leaving one to conclude that these elements had either been neglected or that they failed to find their way into the books of history. While historical records prove that the special approach adopted by the Holy Prophet of Islam (PBUH) in inviting others to Islam had made great impacts, his approach was eventually ignored and discarded following his demise; and as a matter of fact, it is unclear as to how well-versed the commanders who had conquered Iran – and who were the representatives of the caliphate – were with the true message and tenets of Islam.
On the other hand, the Sassanian government of Iran had been facing a severe crisis during this period and since the Zoroastrian religion played a significant role in the social and political foundations of the country, the emergence of any catastrophe in the political set-up would inevitably result in a crisis in the fabric of this religion and the powerful Zoroastrian priests. Thus, with the permeation of decadence and vulnerability in the Sassanian Dynasty, the foundation of the Zoroastrian religion, too, became shaky as a result of which religions like Christianity and Buddhism were provided with the opportunity to flourish.Nonetheless, during the time of the Arab onslaught on the Iranian lands, the powerful Zoroastrian priests who in many ways dominated the lives of the general masses and the other social classes and showed serious resistance to any kind of reforms or change did not enjoy the necessary acceptance and popularity to be able to defend the existing political and religious instructions. Moreover, the aristocrats as well the framers who were mainly concerned with protecting their own positions compromised with the invaders and began trading with them. Besides the two major battles of Nahāvand and Qādesiyah that resulted in the total collapse of the Sassanid rule in Iran, the resistance shown by the Iranians was of varying degrees in the various parts of Iran and in some regions and cities like Rey, the existing rivalry among the influential families for gaining power expedited the advancement of the Muslims. By going through all the available historical records it can be concluded that there was either the lack of a common element that could unite the Iranian masses to put up military and religious resistance against the Arabs or they lacked the necessary strength.The early Muslims gave the Iranians the option to either accept Islam or to continue with their Zoroastrian faith and to instead pay the “jaziyah” (a protection tax that the peoples of other faiths were required to pay to the Muslim governments since the non-Muslims were not obliged to serve in the army). While some non-Muslims may have considered this tax as discriminatory, the jaziyah was significantly lesser than the heavy taxes that had been exacted by the Sassanid kings of Iran as well as the Byzantine rulers of the West and, therefore, it did not seem particularly onerous to most of the non-Muslim citizens. However, the situation did not continue to remain the same and along with the alterations in the nature of the institution of the caliphate, the attitude of the Arabs towards their conquests began to change to a great extent. What can be inferred from the historical records is that even though the Iranians had been freed from the earlier class system of the Sassanid society, they were now faced with a community that imposed a new form of social class system upon them. It is a well-known fact that following the coming into power of Muawiyah, the caliphate had changed into some sort of an Arabian monarchy because by resorting to vague political and economic reasons and under his own particular interpretation of Islam, Muawiyah had aimed at expanding and strengthening the foundations of the Ummayid rule and to add to his lands. There were times during which the Iranians were forced to pay the jizyah taxes even after they had become Muslims in order to ensure that the treasuries of the caliphate were not depleted. The racial attitudes of the Ummayids provoked the Iranians to support all calls for opposition, and particularly the one raised in Iraq, which was the land of their forefathers and mainly due to the fact that the Iranians found a closer affinity to the teachings of the Ahl al-Bayt of the Prophet of the Islam (s) and the views of the Shiites who were from among the strongest opponents of the oppressive Ummayid rule. The most prominent example of the participation of the Iranians in such opposition movements can be found in the movement of Mokhtār Thaqafi which had been inspired in order to avenge the blood of Imām Hosayn (‘a), the brutally slain grandson of the Prophet of Islam (s). Similarly, there are evidences to prove the inclination of the Iranians to gain freedom from Arab domination without actually abandoning Islam. A sentence mentioned by Bosr bin Artāh, the brutal commander of Muawiyah, to a mawāli alleging that “your language may be Arabic but you are Persian at heart”, highlights this sentiment.
Undoubtedly, there were some famous rebel leaders who held anti-Islamic feelings and who aimed at reviving the Persian Empire and gaining local independence in some parts of Iran or who made false claims to prophethood. However, it should not be forgotten that such movements never gained success in attracting the masses and the influential classes of society and even their political and cultural influences faded away in no time. This atmosphere prevailed at a time when towards the end of the first Hejira century Abu Muslim was busy organizing anti-Ummayid uprisings in Khorāsān and in Transoxiania by emphasizing on Islamic values, and especially on those which had been forgotten during the Ummayid rule, and by introducing him and his supporters as ardent Muslims.
The adoption of such a balanced approach from the belief point of view proved to be very effective in attracting elements from the various social classes. However, it should also be noted that the idea of overthrowing the Ummayids was in itself a crucial factor that prompted the Iranians to join the movement of Abu Muslim Khorāsāni, notwithstanding their particular religious beliefs. In any case, the assassination of Abu Muslim in the year 137 AH/754 AD led to the emergence of some radical inclinations among such elements, any action on the part of which had earlier been curtailed by the power of Abu Muslim, and who now found the conditions ripe for promoting their activities. The first century of the Abbasid rule witnessed successive uprisings by people who tended to legitimize their moves by either claming to avenge Abu Muslim’s blood or by making claims of prophethood only in order to gain power. What needs to be noted here, however, is that the sources that have reported these uprisings and the claims made by their leaders are not free from contradictions and baseless inputs. The Beh Āfarid movement that took place in the year 130 AH/748 AD during the lifetime of Abu Muslim Khorāsāni and a little while before the complete defeat of the Ummayids basically aimed at introducing certain reforms in the Zoroastrian religion under the influence of the Islamic teachings and in all probability the Astādesis movement, too, was a follow up of the Beh Āfarid movement and aimed at gaining the same objective.
The Moqanna’ Movement that took place in certain parts of greater Khorāsān and Transoxiania a little while after Abu Muslim’s assassination posed a serious challenge to the caliphate for a few years. The movement started by Yusof Baram in the regions of Herāt, Pushang, and Balkh, simultaneously with the Moqanna’ Movement, was in all probability a branch of the same movement or was at least very closely related to it. Similarly, the uprisings of Sanbād and Eshāq-e Tork that emerged following the assassination of Abu Muslim were apparently in order to avenge his blood.
Although these uprisings would start off in the memory of Abu Muslim, they would deviate from their path because of the ulterior motives of their leaders. Undoubtedly, the Manichaean and the Mazdakite elements that had survived from the Sassanid period played a significant role in these movements and aimed at reviving these faiths. However, the activities of these elements reached a zenith in the movement of Bābak Khorramdin, which emerged in northern Āzarbāyjān towards the end of the 2nd Century AH/8th Century AD, and to some extent spread to the central regions of Iran. As per the historical records of Ibn Nadim, the Khorramdinān or Khorramiyān, who have been named as a branch of the Mazdakites by some scholars, lived in the hilly areas of Āzarbāyjān and by taking advantage of the geographical conditions of their region had managed to form a base for themselves and had launched certain military activities as and when the conditions were found suitable. However, when the power struggle between Amin and Ma’mun (the two sons of the Abbasid Caliph Hārun al-Rashid) had reached its zenith, in which a large number of Iranians, and particularly the people of Khorāsān, supported Ma’mun, Bābak managed to penetrate into the Khorramiyān and posed a serious threat to the caliphate, at least in his region, for about twenty years. A large number of expeditions failed to suppress this movement and it was due to this longstanding resistance that other antagonists could join Bābak’s movement. However, this movement was finally defeated by an Iranian commander from Transoxiania called “Afshin” in the year 222 AH/837 AD.Available sources attribute certain beliefs to the Khorramdinān that are almost similar to those attributed to the other cults of this period. In almost all these sources, some reference has been made to these cults revealing that the Muslims generally referred to them as the “zandiq” (lit.: heretics) because of their Manichaean and Mazdakite inclinations. The central beliefs of these cults, and particularly those of the Khorramites, revolved around reincarnation and the transmigration of the soul from one body to another. It was such beliefs that granted legitimacy to the transference of leadership from one person to another in order to ensure the survival of the movement and the same applied to the movement of Bābak Khorramdin.
A belief in the communal ownership of property and women, a feature commonly shared by the Mazdakites, has also been attributed to the followers of some of these cults and especially the Khorramites. This claim, however, is quite difficult to prove and can only fall under the category of an allegation taking into consideration the marriage of Bābak to the wife of the Khorramite chief, Jāvidān, that took place through a special ceremony, thereby granting no validation to the claim that a trend of communal ownership of women prevailed during that period. As rightly stated by some research scholars regarding Mazdak’s movement, it is quite likely that such efforts on the part of the followers of these cults were only in order to abolish certain undue privileges held by certain members of society and to eliminate the foundations of the class system. Moreover, beliefs regarding the origin of the universe as well as their views on creation were so complicated that they never succeeded in gaining popularity among the masses.
There is no doubt that such movements were initially triggered off by political motives and even if these cults did hold any particular belief structures, they never seemed to have passed on intact to the historians of the following centuries. It was, for instance, said that the Khorramites were not inclined towards conflict and bloodshed and that it was only Bābak Khorramdin who had introduced the alien trend of bloodshed and plunder into this faith whereas there are evidences that prove the presence of violence even before Bābak had joined the Khorramites.
Nevertheless, evidences indicate that an inclination towards political independence as well as the safeguarding of the Islamic faith, with stress upon the original principles of this Divine faith, was a powerful motive that had existed since the times of Abu Muslim Khorāsāni which continued during the various historical events throughout the following centuries. The peak of this trend can be found in the establishment of the Tāherid Dynasty of Khorāsān that had succeeded in gaining relative independence for itself by gaining recognition from the caliphate. From then onwards the Iranians found the opportunity to not only accept Islam but to even have a share in the acceptance of Islam by the other communities, also playing an important role in the growth and spread of Islamic sciences.
Generally speaking, since the Shiite faith considered the establishment of the caliphate following the demise of the noble Prophet of Islam (s) as a deviation from pure Islam, excluding the period of the caliphate of Imam ‘Ali (‘a), it attracted the interest of non-Arab groups of Muslims and especially the Iranians who were already exasperated with the tyranny of the racist Ummayid rule and it is for this reason that Shi’ism has played a significant role in the political and cultural destinies throughout the history of Islamic Iran, exerting various influences in all the social spheres. One of the first incidents that can probably throw light on the Shiite inclination of the Iranians is the movement of Mokhtār Thaqafi that took place in Iraq between the years 64-67 AH/684-686 AD. The mawālis or the converted Iranian Muslims played a fundamental role in this movement and according to certain sources their association with Mokhtār’s movement was mainly inspired by his spurning of the Arab aristocrats and the special attention he paid towards the mawalis with the aim of procuring the rights of the oppressed from the oppressors.Besides some Shiite teachings, and especially those disseminated through the Imams (‘a) which were free of the suggestion of any kind of pan-Arabism, certain Shiite beliefs – like a belief in the appearance of a Divine Savior – which the Iranians were already familiar with through their own pre-Islamic teachings, played a crucial role in attracting them towards Shi’ism. Thus, the presence of a large number of mawālis among the companions of the Shiite Imams, particularly during the reign of the Ummayids is noteworthy. Moreover, the mawālis also had a share in almost all the movements that took off particularly in Iraq at the hands of the Alavids with the aim of overthrowing the Ummayids. For instance, when a well organized movement was formed in Kufa towards the end of the 1st Century AH/7th Century AD, which subsequently spread to as far as Khorāsān, people like Bokir ben Māhān and Abu Salamah Khalāl were two mawālis who played a fundamental role in the formation and leadership of this movement. The prime objective of this movement was to lead anti Ummayyid struggles and to promote one of the descendents of Prophet Mohammad (s), even though the presence of an inclination towards certain Alavid and Abbasid clans cannot be denied; a claim that can be verified through the efforts of Abu Salamah Khalāl’s to convince Imam Sādeq (‘a) to accept the caliphate on the threshold of the downfall of the Ummayyid rule.Alongside the efforts of the leaders of this movement, Yahyā bin Zayd bin ‘Ali (‘a), the grandson of the fourth Shiite Imam (‘a) – whose father’s uprising had been violently thwarted by the Ummayyids and had met indifference from the supporters of the Abbasids in Iraq – managed to win the support of some Shiite Iranians in Khorāsān and the other Eastern regions of Iran like Sarakhs and Balkh to an extent that he could lead a movement in Bayhaq and Neishābur and then spread his activities to Balkh and Herāt. However, Yahyā’s movement was defeated by the Ummayyid army led by Nasr bin Sayyār, the governor of Khorāsān, in Juzjān in the year 125 AH/743 AD and he was himself killed during the course of the battle. Yahyā’s murder was so painful for the Shiites of Khorāsān that they tried to gain solace by naming their sons after him for years to follow.
On the other hand, the Iranians also played an active role in the rather radical movements referred to as the “gholāt” that were considered as part of Shiism. Some ancient historians have even considered these Iranian elements to be of a “magi” origin, perhaps for the simple reason that they found some common elements between their beliefs and the beliefs attributed to the Zoroastrians by the predecessors. The existence of certain elements from Manichaeism and Mazdakism in the belief structure of these groups cannot be totally ruled out.
Nevertheless, in its general sense, the influence of Shiism in the various regions of Iran was so profound that one of the first Alavid rules was established in the Tabarestān of Iran in 250 AH/864 AD, which was led by Hasan bin Zaid – even though it belonged to the Zaidi sect – and lasted until about the first half of the 4th Century AH/10th Century AD. Another Shiite rule in which the Iranians played a far greater role than in the Alavid rule of Tabarestān and through with they ruled for about 130 years over large parts of Iran and Iraq was the government of the Buyids whose reign marks one of the most shinning period of the Islamic culture and civilization and which made a categorical impact on the permeation of Shiite customs and traditions among the people of Iran.Alongside the Buyid rule, there were also other Shiite dynasties that emerged in some parts of Iran such as the Āl-e Hosnaviyah who ruled over parts of Kordestān, Lorestān, and the present-day Khuzistān for about half a century during the 4th and 5th Centuries AH/10th and 11th Centuries AD. There were also some regions in Iran including Rey, Qom, Kāshān, and Sabzevār whose people by and large followed Shiism even though the Shiites did not always rule over these regions. The role of some renowned and influential families of these regions like that of the Ash’aris of Qom, who were the followers of the Shiite Imams (‘a), in the spread of Shiism cannot be taken for granted.
One of the oldest Shiite sects that emerged in Iran was the Ismā’iliyah, which was a well-organized sect whose followers carried out underground and secret political activities. As per historical records, traces of the activities of Mohammad bin Esmā’il can be found in the northern regions of Iran. In the periods that followed they continued to be noticeably active in the territories under the Sāmānid rule as well as in Transoxiania and had managed to attract some of the rulers and commanders of that region to their sectarian faith.
During the Seljuq rule, a branch of the Ismā’ilis called the “Nazāris” led by Hasan Sabbāh, succeeded in establishing an independent rule in the Alamut fortress around the Qazvin region and by making use of the other fortresses of the region gradually extended their influence to the surrounding mountainous areas. Apparently, Hasan Sabbah was more concerned with establishing the concept of Imamate rather than spreading the Ismā’ili teachings on creation and the universe and he, therefore, opposed the Abbasid Caliphate who were generally served by the Seljuqs and their Iranian ministers. Despite repeated bloody conflicts with the Seljuq rulers, the Ismā’ilis succeeded in preserving their status and position for over 150 years but when the Mongols invaded Iran and conquered the Alamut and other fortresses in 654 AH/1256 AD, they were finally defeated and their power and influence was diminished to a great extent.
Following the collapse of the Abbasid caliphate and the conquest of Baghdad by the Mongols the inclination for the establishment of a Shiite rule (and particularly the Ithanā Ashari form of Shiism) gained momentum and one of the Ilkhanids of Iran, Soltān Mohammad Oljāitu, also embraced Shiism. The Sarbedārān Movement of Khorāsān that apparently began as an anti-Mongol development with Sufi inclinations and later turned into a local rule in Sabzevār and its surrounding regions was perhaps the first outstanding effort to establish an Ithnā Ashari Shiite rule during that period of the history of Iran. The Sarbedārān rule lasted only for about fifty years (737-788 AH/1337-1386 AD) and it apparently faced many conflicts and wars during this period. However, the interaction between Sufi teachings and the teachings of Ithna Ashari Shiism gave birth to a movement started by the Safavid dynasty about a century later. As per historical evidences the Safavids had also toyed with the idea of convincing some of the Shiite scholars of Jabal Āmel of Lebanon, including Mohammad bin Makki popularly known as “Shahid-e Awwal” (martyred in 786 AH), to migrate to Khorāsān to disseminate Shiism.
During the same period a number of radical movements took place in the name of Shiism none of which gained much success. The most important of such movements was that of the Horufis which had even continued under the name of the “Noqtaviyeh” until the reign of the Safavid king Shāh Abbās I. The leader of this sect was Fazollāh Astarābādi who was known to be a Sufi and who had proclaimed himself as the “Awaited Twelfth Imam” of the Shiites in the year 786 AH and had made his followers swear allegiance to him for an uprising, dispatching them to different towns and cities to propagate his movement. However, he did not gain much success and finally sought asylum with Mirān Shāh, the son of Tamerlane, in Shirvān who assassinated him on his father’s demand in the year 804 AH/1402 AD. Following the assassination of Fazlollāh Astarābādi, the Horufis more or less continued under the inspiration of his ideals, and at times, even caused some problems for Tamerlane’s successors. For instance, as narrated in the books of history, one of the Horufis called “Ahmad Lor” had made an unsuccessful assassination attempt on Shāhrokh that resulted in a severe retaliation towards the followers of this sect.
Towards the end of the 8th Century and the beginning of the 9th Century AH a few minor local Shiite governments ruled over some parts of Iran. These local governments included the Mar’ashi Seyyeds of Māzandarān, the Kiā’iyāns of Gilān, and the Mosha’sha’iyān of Khuzestān, during whose reigns the Safavid government emerged as the central government of Iran.
Apparently, during this period there was a strong urge among the Iranians for the establishment of a powerful central government that would recognize the Ithnā Ashari school of Shiism as the official religion of the country. However, none of these minor dynasties were powerful enough to fulfill this urge and it was only the Safavid Dynasty that could establish such a rule, mainly because it had managed to create a strong organization on the basis of the Sufi support that it enjoyed both inside Iran as well as outside the usual boundaries of the country. There is no convincing evidence to show that Sheikh Safi al-Din Ardabili (735 AH/1335 AD), the great grandfather of the Safavids – who was the Sufi Sheikh of his times – had any political inclinations, even though as a Sufi Sheikh, he was immensely revered by his numerous followers as well as some of the elite and rulers of his times. However, his successors in Āzarbāyjān, the Caucasus, and Anatolia – particularly after getting related to the Āq Qoyunlu rulers through marriage – organized the Sheikh’s followers into a devoted army. When the leadership of the Sheikh’s followers fell into the hands of Esmā’il, the son of Khwajeh Ali – one of the great grandchildren of Sheikh Safi – he was no more than a young child. Esmā’il fled to Gilān in order to save himself from the Āq Qoyunlu rulers who had realized the intention of the Safavids. However, in the year 905 AH/1500 AD, while he was still very young, Esmā’il returned to Ardabil, accompanied by a small number of his close and trusted associates who had probably encouraged him on this move, and eventually took the reigns of power into his hands, declaring himself as the king (the Shah of Iran) and Ithnā Ashari Shiism as the state religion of Iran in 907 AH/1502 AD.
 Bahramian , Ali “Iran Entry” The Great Islamic Encyclopedia. Ed. Kazem Musavi Bojnourdi.Tehran: The Center of Great Islamic Encyclopaedia , 1989-, V.10 ,pp.589 – 593