mastery vs rulership

mastery

noun
  • The position or authority of a master; dominion; command; supremacy; superiority. 

  • Superiority in war or competition; victory; triumph; preeminence. 

  • The act or process of mastering; the state of having mastered; expertise. 

rulership

noun
  • A position in which one rules or has sovereignty over others. 

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