Celts or Gauls are an ethno-linguistic group of tribal societies in the Iron Age and medieval Europe who spoke Celtic languages and had cultural similarities, although the relationship between ethnic, linguistic and cultural elements is still uncertain and controversial.
The earliest archaeological culture that can reasonably be considered Proto-Celtic is the burial field culture (1300-750 BC) of the Late Bronze Age of Central Europe, which flourished around 1200 BC.
Its continuation was the completely Celtic culture of the Iron Age – the Hallstatt culture (c. 800-450 BC), named after a rich grave located in Hallstatt (Austria).
Subsequently, the La Tene culture (c. 450 BC before the Roman conquest) replaces the Hallstatt culture . This culture spread through migrations to the British Isles (Isle Celts), France and the Netherlands (Gauls), the Czech Republic, Poland and most of Central Europe, as well as the Iberian Peninsula (Celtiberians, Galicia) and Northern Italy (Holassex culture and Cisalpine Gauls), and after the Gallic invasion of the Balkans in 279 BC, and eastward to central Anatolia (state of Galatia).
In the II-I centuries. BC. the Celtic culture began to decline and the Celts suffered one defeat after another. Rome invades southern France. Celts are being ousted from Germany and Central Europe. Finally, in the years 59-51. BC. Julius Caesar captures all of Gaul.
By the middle of the 1st millennium AD. e., due to the expansion of the Roman Empire and the Great Migration, Celtic culture began to be limited to Ireland, the western and northern parts of Great Britain (Wales, Scotland, and Cornwall), the Isle of Man and the Brittany Peninsula (Western France). Between the 5th and 8th centuries, the Celtic-speaking communities in these regions became fairly tight-knit cultural communities. They shared a common linguistic, religious and artistic heritage that set them apart from the surrounding peoples. However, by the 6th century, the continental Celtic languages were no longer in widespread use.