Serpentine vs Swat

Serpentine

name
  • A river in Canada. 

  • A river in New Zealand. 

  • The lake in Hyde Park, London. 

  • A river in Alaska. 

  • A river in Australia. 

Swat

name
  • a river in NWFP administrative province of Pakistan 

  • a valley and a district in NWFP administrative province of Pakistan 

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