The Slovaks and Czechs are a recent example, but even most Slavs were undifferentiated as recently as 600 AD - Poles, Czechs, East Slavs, Southern Slavs spoke the same language and were one "ethnicity"
Even Germanics spoke similar languages around the time of Christ
Nebelivka
Thanks all, these were probably ancestors of someone later found along the shores of the Med and Aegean.
East Bulgaria Reveals Minoan Pertainence
http://www.freerepublic.com/focus/news/1326899/posts
German Scientists: Europe’s Oldest Script Found In Bulgaria (Minoan)
http://www.freerepublic.com/focus/news/1406648/posts