The Proto-Celtic language, also called Common Celtic, is the reconstructed ancestor language of all the known Celtic languages. Its lexis can be confidently reconstructed on the basis of the comparative method of historical linguistics. Proto-Celtic is a branch of the Western Indo-European languages, along with the other branches Italic, Germanic, Hellenic, Indo-Iranian, Albanian and Balto-Slavic. The exact relationships between these branches are under discussion. The earliest archaeological culture that may justifiably be considered as Proto-Celtic is the Late Bronze Age Urnfield culture of Central Europe from the last quarter of the second millennium BC. By the Iron Age Hallstatt culture of around 800 BC, these people had become fully Celtic.

The Proto-Celtic language, also called Common Celtic, is the reconstructed ancestor language of all the known Celtic languages. Its lexis can be confidently reconstructed on the basis of the comparative method of historical linguistics. Proto-Celtic is a branch of the Western Indo-European languages, along with the other branches Italic, Germanic, Hellenic, Indo-Iranian, Albanian and Balto-Slavic. The exact relationships between these branches are under discussion. The earliest archaeological culture that may justifiably be considered as Proto-Celtic is the Late Bronze Age Urnfield culture of Central Europe from the last quarter of the second millennium BC. By the Iron Age Hallstatt culture of around 800 BC, these people had become fully Celtic.