Yarsanism, Ahl-e Haqq or Kaka'i ( or ; , ), is a syncretic religion founded by Sultan Sahak in the late 14th century in western Iran. The total number of followers of Yarsanism is estimated to be over half a million to one million in Iran. The numbers in Iraq are unknown. Followers are mostly Kurds from the Guran, Sanjâbi, Kalhor, Zangana and Jalalvand tribes. Turkic-speaking Yarsan enclaves also exist in Iran. Some Yarsanis in Iraq are called Kaka'i. Yarsanis say that some people call them disparagingly as "Ali-o-allahi" or "worshipers of Ali", labels which Yarsanis deny. Many Yarsanis hide their religion due to the pressure of Iran's Islamic system, and there are no exact statistics of their population. The Yarsanis have a distinct religious literature primarily written in the Gorani language. However, few modern Yarsani can read or write Gorani as their mother tongue is Southern Kurdish or Sorani. Their central religious book is called the Kalâm-e Saranjâm, written in the 15th century and based on the teachings of Sultan Sahak. Geography The majority of Yarsan followers live in Kermanshah Province and adjacent areas of Lorestan Province and Ilam Province in Iran. They are the predominant religious population in Mahidasht, Bivanij and Zohab districts of Kermanshah, and populate rural areas of Delfan, Holeylan and Posht-e Kuh in Ilam and Lorestan. The main urban centers of the religion are Sahneh, Kerend-e Gharb and Gahvareh, and other important cities include Kermanshah, Sarpol-e Zahab and Qasr-e Shirin. Other areas in Iran with a significant Yarsan population include Hashtgerd and Varamin near Tehran and Maragheh, and Tabriz in Iranian Azerbaijan, where important Turkic-speaking Yarsan communities live and use Turkic for many of their religious texts. The Yarsani tradition claims that all early communities used Gorani as their religious language, but that over time, some groups were forced to adopt a Turkic language closely akin to Azeri for all purposes, including religion. In Iraq, Yarsan followers mainly live in Iraqi Kurdistan, around Mosul, Kirkuk, Kalar, Khanaqin, Erbil, Sulaymaniyah, and Halabja. Beliefs The Yarsani follow the mystical teachings of Sultan Sahak ( 14th-15th century). From the Yarsani point of view, the universe is composed of two distinct yet interrelated worlds: the internal (bātinī) and the external (zāhirī), each having its own order and rules. Although humans are only aware of the outer world, their lives are governed according to the rules of the inner world.