emir vs grand dukedom

emir

noun
  • A prince, commander or other leader or ruler in an Islamic nation. 

  • A descendant of the prophet Muhammad. 

grand dukedom

noun
  • The title of grand duke or grand duchess, with its pertaining privileges and obligations; contrast grand duchy. 

How often have the words emir and grand dukedom occurred in a corpus of books? (source: Google Ngram Viewer )