Celts (pronounced /ˈkɛlts/ or /ˈsɛlts/, see names of the Celts) is a modern term used to describe any of the European peoples of antiquity who spoke a Celtic language.

The historical Celts were a diverse group of tribal societies in Iron Age Europe. Proto-Celtic culture formed in the Early Iron Age (1200 BC-400 AD) in Central Europe (Hallstatt period, named for the site in present-day Austria). By the later Iron Age (La Tène period), this Celtic culture had expanded over a wide range of lands, whether by diffusion or migration: to the British Isles (Insular Celts), the Iberian Peninsula (Celtiberians), much of Central Europe, (Gauls) and following the Gallic invasion of the Balkans in 279 BC as far east as central Anatolia (Galatians)