period piece vs remains

period piece

noun
  • A work of art or drama which evokes a particular historical era. 

  • A work which evokes the era in which it was produced, but may not have any other especial features. 

remains

noun
  • Historical or archaeological relics. 

  • All that is left of the stock of some things; remnants. 

  • What is left after a person (or any organism) dies; a corpse. 

  • The extant writings of a deceased person. 

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