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.