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