Proto-Indo-European language

Proto-Indo-European (PIE) is the linguistic reconstruction of the common ancestor of the Indo-European languages. PIE was the first proposed proto-language to be widely accepted by linguists. Far more work has gone into reconstructing it than any other proto-language, and it is by far the best understood of all proto-languages of its age. During the 19th century, the vast majority of linguistic work was devoted to reconstruction of Proto-Indo-European or its daughter proto-languages such as Proto-Germanic, and most of the current techniques of linguistic reconstruction in historical linguistics (e.g. the comparative method and the method of internal reconstruction) were developed as a result. These methods supply all of our knowledge concerning PIE, since there is no written record of the language.

Scholars estimate that PIE may have been spoken as a single language (before divergence began) around 3500 BC, though estimates by different authorities can vary by more than a millennium. A number of hypotheses have been proposed for the origin and spread of the language, the most popular among linguists being the Kurgan hypothesis, which postulates an origin in the Pontic–Caspian steppe of Eastern Europe. Features of the culture of the speakers of PIE, known as Proto-Indo-Europeans, have also been reconstructed based on the shared vocabulary of the early attested Indo-European languages.