Bey is a Turkish title for "chieftain," traitionally applied to the leaders of small tribal groups. In historical accounts, many Turkish, other Turkic and Persian leaders are titled Bey, Beg or Beigh. They are 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 second (the equivalent of duchy in Europe). Today, the word is used as a social title for men (like the English word "mister").