bey vs tsar

bey

noun
  • A governor of a province or district in the Turkish dominions 

  • in various other places, a prince or nobleman 

tsar

noun
  • A person with great power; an autocrat. 

  • An emperor of Russia (1547 to 1917) and of some South Slavic states. 

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