tumulus vs urnfield

tumulus

noun
  • A mound of earth, especially one placed over a prehistoric tomb; a barrow. 

urnfield

noun
  • Ground used as a cemetery in Bronze Age Europe, in which the ashs of cremations were buried in cinerary urns. 

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