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Old European (German: Alteuropäisch) is the term used by Hans Krahe (1964) for the language of the oldest reconstructed stratum of European hydronymy (river names) in Central and Western Europe. The character of these river names is pre-Indo-European (i.e., pre-Italic, pre-Germanic and pre-Celtic) and dated by Krahe to the 2nd millennium BC.

Krahe writes in A1, chapter III, "Introducing preface" Number 2 that the old European hydronomy extended from Scandinavia to South Italy, from Western Europe including the British Isles to the Baltic countries. Of the three Mediterranean peninsulas, Italy was most completely included, whilst the Balkan Peninsula was only scarcely covered. He writes that what he presents for hydronomy also applies to mountains and ranges of mountains, and continues with "Karpaten" and "Karawanken", certainly within the Slavic settlement area, omitting the Bavarian/Austrian "Karwendel" though. This area is associated with the spread of the later "Western" Indo-European dialects, the Celtic, Italic, Germanic, Baltic, and Illyrian branches. Notably exempt is Greece.

Krahe located the geographical nucleus of this area as stretching from the Baltic across Western Poland and Germany to the Swiss plateau and the upper Danube north of the Alps, while he considered the Old European river names of southern France, Italy and Spain to be later imports, replacing "Aegean-Pelasgian" and Iberian substrates, corresponding to Italic, Celtic and Illyrian "invasions" from about 1300 BC.

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