Persia was a Sunni country initially, from the days it was conquered by Muslims in the caliphate of ‘Omar [ra]. It was much later, around the sixteenth century, that a Shia dynasty , the Safavids, whose founder was not even Persian, converted Persia into a Shia country by force.
Mulla Baqir Majlisi, the grand mulla of Shia cult, was the product of the same Safavid dynasty. This alone refutes the myth of many nationalist, anti-Islamic Iranians who claim that Iranians have chosen Shi’ism from day one to cover their Batini (hidden) beliefs of Zoroastrianism and ancient Iranian culture, i.e. they made up their own “Islam”. While it is true that Tashayyu’ (Shi’ism), particularly twelver Imamism has mnay Iranian elements, yet it is ridiculous to claim that Iranians have chosen Shi’ism to hide protect their pre-Islamic beliefs, for Iranians were staunch Sunnis and in fact the leaders of the Islamic world in terms of science for most of Iran’s history (over 900 years!). No nation can produce giants like Imam Muslim Nishapouri, Imam Ghazali, Saadi, Hafiz (all Sunnis) except with deep love and adherence to the religion of manking (Islam). Anyway, here some information about the sudden change of Iran’s Islamic history:
Encyclopedia Iranica says:
It might indeed be argued that the rise to power of the Safavids constituted another Turkic invasion of Persia, one proceeding from the west rather than the east; insofar as the ancestors of the Qezelbāš had once passed through Persia en route to Anatolia, it might also be called a case of nomadic reflux. The ultimate result was, however, the formation of a distinctively Persian state dedicated to the propagation of Shiʿism. Although coercion played a large part in the initial stages of this venture, it is plain that far more was involved in the profound and lasting assimilation of Shiʿism that took place, which transformed Persia and made of it the principal stronghold and even—in an ahistorical sense—the homeland of Shiʿism.
It was, however, nothing less than a reign of terror that inaugurated the new dispensation. On capturing Tabriz in 907/1501, a city two-thirds Sunnite in population, Shah Esmāʿil threatened with death all who might resist the adoption of Shiʿite prayer ritual in the main congregational mosque, and he had Qezelbāš soldiers patrol the congregation to ensure that none raise his voice against the cursing of the first three caliphs, viewed as enemies of the Prophet’s family. In Tabriz and elsewhere, gangs of professional execrators known as the tabarrāʾiān would accost the townsfolk at random, forcing them to curse the objectionable personages on pain of death. Selective killings of prominent Sunnites occurred in a large number of places, notably Qazvin and Isfahan, and in Shiraz and Yazd, outright massacres took place. Sunnite mosques were desecrated, and the tombs of eminent Sunnite scholars destroyed (Aubin, 1970, pp. 237-38; idem, 1988, pp. 94-101). http://www.cultureofiran.com/islam_safavid_era.html
Again quoting from Encyclopedia Iranica
Encyclopedia Iranica says:
The near-complete eradication of Sunnism from the Iranian plateau, achieved by these and other means, must clearly have been gradual, and at least in some places it consisted initially of the pragmatic and superficial acceptance of a coerced creed. The Sunnite notables of Qazvin in particular proved obdurate, and several of them were executed during the reign of Shah Ṭahmāsb for religious deviance (Bacqué-Grammont, p. 83, n. 231). Nonetheless, enough of them survived to qualify (or claim to qualify) for the reward offered by Esmāʿil II during his brief Sunnite interregnum to all who had steadfastly refused to curse the first three caliphs (Golsorkhi, p. 479). There is evidence, too, for the persistence of Sunnite loyalties in some localities into the reign of ʿAbbās I, particularly in eastern Persia. In 1008/1599 he launched a campaign of persecution against the Sunnites of Sorḵa (Semnān), but three decades later Sunnismwas still widespread in the city, although less so in its environs. http://www.cultureofiran.com/islam_safavid_era.html
We read in Rethinking world history: essays on Europe, Islam, and world history by Marshall G. S. Hodgson, Edmund Burke ,p. 195
Ismail, the head of the Shi’ite Safawiyya tariqas – which had the roots of its power in the decentralized ways of the late Middle Ages and which depended for its military strength on tribal Turks as was so characteristically the case at that time – seems to have participated many of the events. He set about conquering, at the star of the sixteenth century, as much of the Dar al-Islam as possible and forcing the Sunni populations to adopt Shi’ism. He failed to convert all Islam to the Shi’a, but he did carve out a lasting empire in Iran, the Safavid empire. There he insisted that everyone should publicly curse such heroes of early Islam as Umar and Abu Bakr and follow the Shi’ite form of the Sharia. The Sunni Tariqas were braught in hastily from whatever corners of Islam – chiefly Arab – the Shia had been strong in, and the autonomus body of Shi’ite mujtahids – authorized leading interpreters of the sharia gained an undisputed ascendancy. Muhammad Baqir al-Majlisi, in the seventeenth century, was especially effective in putting the doctrine into definitive form with the aid of the political authorities. The areas incorporated in the Safavid empire, Persian, Turkish , or Arab speaking, have been insistently Shi’ite since. Rethinking world history: essays on Europe, Islam, and world history by Marshall G. S. Hodgson, Edmund Burke , p. 195
Roger Savory says in his book ‘Iran Under the Safavids’ p. 27 to 29
Shias therefore regard the first three Caliphs (Abu Bakr, Umar and Uthman) as usurpers, and the ritual of cursing of these persons has always been a proper duty of Shias, although the emphasis on it varied from time to time. In the early days of the Safavid state, when revolutionary fervous was still strong, great emphasis was palced on this ritual of cursing. Safavid supporters known as tabarraiyan walked through the streets and bazaars cursing not only the three “rightly guided” caliphs mentioned above, but also the enemies of Ali and the other Imams, and Sunnis in general. Anyone who failed to respond without delay, “May it [the cursing] be more and not less”. was liable ot be put to death on the spot. Despite the two centuries of propaganda carried out by Safavids, the promulgation of Shiism as the state religion was fraught with danger, and some of Ismail’s advisers were worried about the reaction to his announcement. “Of the 200,000-300,000 people in Tibriz”, they said “two thirds are Sunnis … we fear that the people may say they do not want Shii sovereign, and if (Which God forbid!) the people rject Shi’ism, what can we do about it?” Ismail’s reply was uncompromising: he had been comissioned to perform this task, he said, and God and the immaculated Imams were his companions, he feared no one. “With God’s help,” he said, “if the people utter on word of protest, I will draw the sword and leave not one of them “
Colin Turner says in ‘The rise of religious externalism in Safavid Iran’ p. 84
The suppression of Sunnism was not something that could be taken lightly, given the fact that the vast majority of the populace was Sunni. The ritual vilification of the first three ‘rightly guided’ Caliphs (al Kuhulufa al rashidun), Abu Bakr, Umar and Uthman, was rigidly enforced, with bands of zealous Twelver faithful formed in each town to ensure that people adhered to the new anti Sunni instruction … Although all Twelver Shiite teaching is , by its very nature, implicitly anti Sunni, the kind of explicit attacks made upon the leading figure of Sunnism by the externalist Twelver fuqaha in Iran at the beginning of the Safavid period was unprecedented. According to a treatise written by Karaki, the cursing of the Caliphs, known as la’n, became a religious duty (wajib) , in another tract the Sunnis were declared impure (najis), a ruling which in effect reduced them in the eyes of the Twelver Shi’ites to the level of dogs, swine, infidels and other such Islamically-defined objects of impurity.
Patrick Cockburn says in ‘Muqtada al-Sadr, the Shia revival, and the struggle for Iraq’ p. 25
The first Safavid Shah, Ismail, a Turkish speaking warrior who established his capital in Tibriz, seized power in Iran in 1501. He used Twelver Shi’ism as the ideological glue to bind his disparate new realm to his dynasty through forced conversion. Shi’ite clergy were imported from Lebanon and Bahrain to indocrinate Iranians. The first three caliphs – Abu Bakr, Omar, and Othman – who had displaced Ali were formally cursed during Friday sermons.