ascendancy vs overlordship

ascendancy

noun
  • Supremacy; dominant control; the quality of being in the ascendant. 

  • A class of Protestant landowners and professionals that dominated political and social life in Ireland up to the early 20th century 

  • A quantitative attribute of an ecosystem, defined as a function of the ecosystem's trophic network, and intended to indicate its ability to prevail against disturbance by virtue of its combined organization and size. 

overlordship

noun
  • The position or quality of being an overlord. 

  • The realm of overlords. 

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