Shi'ism in the 4th/10th Century
In the 4th/10th century certain conditions again prevailed which aided greatly the spread and strengthening of Shi'ism. Among them were the weaknesses that appeared in the central Abbasid government and administration and the appearance of the Buyid rulers. The Buyids, who were Shi'ite had the greatest influence not only in the provinces of Persia but also in the capital of the caliphate in Baghdad, and even upon the caliph himself.
This new strength of considerable proportions enabled the Shi'ites to stand up before their opponents who previously had tried to crush them by relying upon the power of the caliphate. It also made it possible for the Shi'ites to propagate their religious views openly.
As recorded by historians, during this century most of the Arabian peninsula was Shi'ite with the exception of some of the big cities. Even some of the major cities like Hajar, Uman, and Sa'dah were Shi'ite. In Basra, which had always been a Sunni city and competed with Kufa which was considered a Shi'ite center, there appeared a notable group of Shi'ites. Also in Tripoli, Nablus, Tiberias, Aleppo, Nayshapur, and Herat there were many Shi'ites, while Ahwaz and the coast of the Persian Gulf on the Persian side were also Shi'ite.
At the beginning of this century Nasir Utrush, after many years of propagation of his religious mission in northern Persia, gained power in Tabaristan and established a kingdom which continued for several generations after him. Before Utrush, Hasan ibn Zayd al-'Alawi had reigned from many years in Tabaristan. Also in this period the Fatimids, who were Isma'ili, conquered Egypt and organized a caliphate which lasted for over two centuries (296/908-567/1171). Often disputation and fighting occurred in major cities like Baghdad, Cairo and Nayshapur between Shi'ites and Sunnis, in some of which the Shi'ites would gain the upper hand and come out victorious.
Shi'ism from the 5th/11th to the 9th/15th Centuries
From the 5th/11th to the 9th/15th centuries Shi'ism continued to expand as it had done in the 4th/10th century. Many kings and rulers who were Shi'ite appeared in different parts of the Islamic world and propagated Shi'ism. Toward the end of the 5th/11th century the missionary activity of Isma'ilism took root in the fort of Alamut and for nearly a century and a half the Isma'ilis lived in complete independence in the central regions of Persia. Also the Sadat-i Mar'ashi, who were descendants of the Holy Prophet, ruled for many years in Mazandaran (Tabaristan).
Shah Muhammad Khudabandah, one of the well-known Mongol rulers, became Shi'ite and his descendants ruled for many years in Persia and were instrumental in spreading Shi'ism. Mention must also be made of the kings of the Aq Qoyunlu and Qara Qoyunlu dynasties who ruled in Tabriz and whose domain extended to Fars and Kerman, as well as of the Fatimid government which was ruling in Egypt.
Of course religious freedom and the possibility of exerting religious power by the populace differed under different rulers. For example, with the termination of Fatimid rule and coming to power of the Ayyubids the scene changed completely and the Shi'ite population of Egypt and Syria lost its religious independence.
Many of the Shi'ites of Syria were killed during this period merely on the accusation of following Shi'ism. One of these was Shahid-i awwal (the First Martyr) Muhammad ibn Makki, one of the great figures in Shi'ite jurisprudence, who was killed in Damascus in 786/1384. Also Shaykh al-ishraq Shihab al-Din Suhrawardi was killed in Aleppo on the accusation that he was cultivating Batini teachings and philosophy.
Altogether during this period Shi'ism was growing from the point of view of numbers, even though its religious power and freedom depended upon local conditions and the rulers of the time. During this period, however, Shi'ism never became the official religion of any Muslim state.
Shi'ism in the 10th/16th and 11th/17th Centuries
In the 10th/16th century Isma'il, who was of the household of Shaykh Safi al-Din Ardibili (d. 735/1334), a Sufi master and also a Shi'ite, began a revolt in Ardibil, with three hundred Sufis who were disciples of his forefathers, with the aim of establishing an independent and powerful Shi'ite country. In this way he began the conquest of Persia and overcame the local feudal princes. After a series of bloody wars with local rulers and also the Ottomans who held the title of caliph, he succeeded in forming Persia piece by piece into a country and in making Shi'ism the official religion in his kingdom.
After the death of Shah Isma'il other Safavid kings reigned in Persia until the 12th/18th century and each continued to recognize Shi'ism as the official religion of the country and further to strengthen its hold upon this land. At the height of their power, during the reign of Shah 'Abbas, the Safavids were able to increase the territorial expansion and the population of Persia to twice its present size. As for other Muslim lands, the Shi'ite population continued the same as before and increased only through the natural growth of population.
Shi'ism from the 12th/18th to the 14th/20th Centuries
During the past three centuries Shi'ism has followed its natural rate of growth as before. At the present moment, during the latter part of the 14th/20th century, Shi'ism is recognized as the official religion in Iran, and in the Yemen and Iraq the majority population is Shi'ite. In nearly all lands where there are Muslims one can find a certain number of Shi'ites. It has been said that altogether in the world today there are about eighty to ninety million Shi'ites.