The Kurdish population is estimated to be between 30 and 45 million. Most Kurdish people live in Kurdistan, which today is split between Iranian Kurdistan, Iraqi Kurdistan, Turkish Kurdistan, and Syrian Kurdistan.
The bulk of Kurdish groups in Kurdistan are Sunni (mostly of the Shafi'i school), but there are significant minorities adhering to Shia Islam (especially Alevis), Yazidism, Yarsanism, Christianity and Judaism.
Kurds in Turkey and Kurds of Central Anatolia
According to a report by Turkish agency KONDA, in 2006, out of the total population of 73 million people in Turkey there were 11.4 million Kurds and Zazas living in Turkey (close to 15.68% of the total population). The Turkish newspaper Milliyet reported in 2008 that the Kurdish population in Turkey is 12.6 million; although this also includes 3 million Zazas. According to the World Factbook, Kurdish people make up 18% of Turkey's population (about 14 million, out of 77.8 million people). Kurdish sources put the figure at 10 to 15 million Kurds in Turkey.
Kurds mostly live in Northern Kurdistan, in Southeastern and Eastern Anatolia. But large Kurdish populations can be found in western Turkey due to internal migration. According to Rüstem Erkan, Istanbul is the province with the largest Kurdish population in Turkey.
Kurds in Iran and Kurds of Khorasan
From the 7 million Iranian Kurds, majority who are Sunni. Shia Kurds inhabit Kermanshah Province, except for those parts where people are Jaff, and Ilam Province Province; as well as some parts of Kurdistan, Hamadan and Zanjan provinces. The Kurds of Khorasan Province in northeastern Iran are also adherents of Shia Islam. During the Shia revolution in Iran the major Kurdish political parties were unsuccessful in absorbing Shia Kurds, who at that period had no interest in autonomy. However, since the 1990s Kurdish nationalism has seeped into the Shia Kurdish area partly due to outrage against government's violent suppression of Kurds farther north.
Kurds in Iraq
Kurds constitute approximately 17% of Iraq's population.