administrative unit vs fief

administrative unit

fief

noun
  • A territory, a domain, an area over which one exercises lordly control, particularly with regard to corporate or governmental bureaucracies. 

  • Land held of a superior, particularly on condition of homage, fealty, and personal service, especially military service. 

  • Synonym of estate: any land, when considered as a region over which the owner exercises lordly control. 

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