The Curonians or Kurs (Curonian: Korsi; German: Kuren; Latvian: kurši; Russian: курши; Old East Slavic: кърсь; Lithuanian: kuršiai; Estonian: kuralased; Polish: Kurowie) were a Baltic tribe living on the shores of the Baltic Sea in what are now the western parts of Latvia and Lithuania from the 5th to the 16th centuries, when they merged with other Baltic tribes. They gave their name to the region of Courland (Kurzeme), and they spoke the Old Curonian language. Curonian lands were conquered by the Livonian Order in 1266 and they eventually merged with other Baltic tribes participating in the ethnogenesis of Lithuanians and Latvians.
The ethnic origin of the Curonians has been disputed in the past. Some researchers place the Curonians in the eastern Baltic group. However, others hold that the Curonians were related to Old Prussians who belonged in the western Baltic group.