Proto-Indo-European language

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

PIE is estimated to have been spoken as a single language around 3500 B.C.E. during the Neolithic Age, though estimates vary by more than a thousand years. According to the prevailing Kurgan hypothesis, the original homeland of the Proto-Indo-Europeans may have been in the Pontic–Caspian steppe of Eastern Europe. Work has also gone into reconstructing their culture and religion. As Proto-Indo-Europeans became isolated from each other through the Indo-European migrations, the dialects of PIE spoken by the various groups diverged by undergoing certain sound laws and shifts in morphology to transform into the known ancient and modern Indo-European languages.

PIE had a complex system of morphology that included inflectional suffixes as well as ablaut (vowel alterations, for example as preserved in English sing, sang, sung) and accent. PIE nominals and pronouns had a complex system of declension, and verbs similarly had a complex system of conjugation. The PIE phonology, particles, numerals, and copula are also well-reconstructed. Today, the most widely-spoken daughter languages of PIE are Spanish, English, Hindi, Portuguese, Bengali, Russian, Punjabi, German, French, and Marathi.

...
Wikipedia