As the 20th century progressed, the ethnic interpretation of La Tène culture grew to become additional strongly rooted, and any results of La Tène lifestyle and flat inhumation cemeteries have been joined to the Celts and the Celtic language. More recently, Cunliffe proposes that proto-Celtic had arisen in the Atlantic zone even previously, by 3000 BC, and spread eastwards with the Bell Beaker lifestyle above the adhering to millennium.