Azerbaijani, any member of a Turkic people living chiefly in the Republic of Azerbaijan and in the region of Azerbaijan in northwestern Iran. At the turn of the 21st century there were some 7.5 million Azerbaijani in the republic and neighbouring areas and more than 15 million in Iran. They are mainly sedentary farmers and herders, although some of those in the republic have found employment in various industries. Most Azerbaijani are Shīʿite Muslims. They speak Azerbaijani, a language belonging to the southwestern branch of Turkic languages.
The Azerbaijani are of mixed ethnic origin, the oldest element deriving from the indigenous population of eastern Transcaucasia and possibly from the Medians of northern Persia. This population was Persianized during the period of the Sāsānian dynasty of Iran (3rd–7th century ce). Turkicization of the population can be dated from the region’s conquest by the Seljuq Turks in the 11th century and the continued influx of Turkic populations in subsequent centuries, including those groups that migrated during the Mongol conquests in the 13th century. (The greater portion of the tribes that formed the Mongol forces or were stimulated by the Mongol conquest to migrate were Turkic.) Parts of the region later passed variously under the Kara Koyunlu and the Ak Koyunlu, rival Turkic tribal confederations, and, at the beginning of the 16th century, the turcophone Ṣafavid dynasty.