Azerbaijanis or Azeris, also known as Azerbaijani Turks, are a Turkic ethnic group living mainly in the Iranian region of Azerbaijan and the sovereign Republic of Azerbaijan. They are the second-most numerous ethnic group among the Turkic peoples after Anatolian Turks. They are predominantly Shi'i Muslims, and have a mixed cultural heritage, including Turkic, Iranian, and Caucasian elements. They comprise the largest ethnic group in the Republic of Azerbaijan and by far the second-largest ethnic group in neighboring Iran. The world's largest number of ethnic Azerbaijanis live in Iran, followed by the Republic of Azerbaijan.