rivière vs wampum

rivière

noun
  • A necklace of diamonds or other precious stones, especially one of several strings. 

wampum

noun
  • A string of such beads. 

  • Small beads made from polished shells, especially white ones, formerly used as money and jewelry by certain Native American peoples. 

  • Money. 

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