His ancestor Safi ud-Din (1252–1334) was a Sufi holy man and founder of the Safaviyya, the mystic brotherhood after which the dynasty is named. Supported by Turcoman tribesmen, he established his rule over Persia, extending it into Kurdistan and driving the Uzbeks from Khurasan in the north-east. His expansion was checked in the west by the Ottoman sultan Selim I at Chaldiran in 1514. His most enduring achievement was to convert his realm from Sunni to Shia Islam.