Bey's a Turkish title for "chieftain," traditionally applied to the leaders of small tribal groups. In historical accounts, many Turkish, other Turkic and Persian leaders are titled Bey, Beg, Bek, Bay, Baig or Beigh. They're all the same word with the simple meaning of "lord." The regions or provinces where Beys (the equivalent of duke in Europe) ruled or which they administered were called Beylik, roughly meaning "emirate" or "principality" in the first case, "province" or "governorate" in the… (More on Bey)