Islam is by far the most practiced religion in Turkey. Most Turkish people are Sunni Muslims, and most of them belong to the Hanafi school of jurisprudence. Smaller numbers belonging to the Alevi, Ja'fari and Alawite minorities. The established presence of Islam in the region that now constitutes modern Turkey dates back to the later half of the 11th century, when the Seljuks started expanding into eastern Anatolia.
While official records indicate the population of Turkey to be 99.8% Muslim, most surveys estimate the percentage to be around 85 to 95%. The Hanafi school of fiqh (maddhab) of Sunni Islam makes up about 90% of the Muslim population, with the remaining Muslim sects consisting of Alevis (close to 10%), Ja'faris (representing 1%) and Alawites (with an estimated population of around 500,000 to 1 million, or about 1%). With a sizeable part of population being Cultural Muslims, there is also a minority of Sufi and non-denominational Muslims.