Duke and count, at least in western Europe, were old Roman titles. Count is derived from Comes meaning imperial companion, and Duke comes from Dux, meaning military leader.
They didn't found. Hear, in Eastern Europe, we still use titles like boyar, knyaz, veliky knyaz, udel'ny knyaz, domnitor, hetman(etc.) to describe our history. And, for example, in Russia traditional titles was used till 1917, just read russian classics.