La Tène culture marked the heyday of the Celtic people. The so-called Latenian period lasted from 450 BC, with the end of the Hallstatt culture, until the 1st century AD, when Rome conquered Brittany.
Celtic art at this time lived its “Golden Period”, at the same time that a great territorial expansion began, mobilized by the demographic growth and by the pressure of other neighboring peoples. Attacks on the Greco-Roman world in this period were frequent:in 390 BC. Rome is sacked by the Celts, and in 272 BC, so is the sanctuary of Apollo in the Greek city of Delphi.
The Celtic people who came from southeastern Germany, in the 4th century BC. they already occupied the entire Po plain, and in the following century they invaded the Hellenic region and ended up reaching, in 276 BC, Asia Minor, where they established themselves as the well-known Galatians of the Epistles of São Paulo. Thus, at the beginning of the first century BC, Celtic territory stretched from Spain to Asia Minor, from the British Isles to the Po plain.
It is impressive how such a large territory at no time constitutes an Empire with a consistent policy. During this entire period, what united the Celts was not a king, or any other tie of a political nature. Art, language and religion were the only promoters of unity.
At the same time that the great expansion was taking place, the twilight of the Celtic people began, so to speak, essentially motivated by the lack of an organization among the different tribes.