Page "Kurgan hypothesis" Paragraph 25

* Wave 2, mid 4th millennium BC, originating in the Maykop culture and resulting in advances of " kurganized " hybrid cultures into northern Europe around 3000 BC ( Globular Amphora culture, Baden culture, and ultimately Corded Ware culture ).

According to Gimbutas this corresponds to the first intrusion of Indo-European languages into western and northern Europe.