burb vs purlieu

burb

noun
  • A suburb. 

purlieu

noun
  • The outskirts of any place; an adjacent district; the environs or neighborhood. 

  • The ground on the edges of a forest, especially when partly subject to the same forest laws concerning game hunting etc. 

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