myriarchy vs undecimvirate

myriarchy

noun
  • An area controlled by a Mongolian myriarch and theoretically comprising 10,000 households. 

  • A regiment of 10,000 soldiers, especially (historical) a Mongolian toman. 

undecimvirate

noun
  • A group of eleven people, especially (politics) a council of eleven men sharing office or power and particularly (historical) the groups of eleven magistrates in ancient Athens. 

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