Vasconic Substratum Theory

The Vasconic substratum theory is a proposal that many western European languages contain remnants of an old language family of Vasconic languages, of which Basque is the only surviving member. The proposal was made by the German linguist Theo Vennemann, but has been rejected by other linguists. According to Vennemann, Vasconic languages were once widespread on the European continent before they were mostly replaced by Indo-European languages. Relics of these languages include toponyms across Central and Western Europe and some vocabulary in Germanic and Balto-Slavic languages that cannot be traced to a common Indo-European ancestor.