infernal region vs nether region

infernal region

nether region

noun
  • A place which is subterranean or enclosed beneath a surface, especially one which is dark, dank, or otherwise inhospitable. 

  • The private parts between the legs; the groin or buttocks. 

  • Hell; a realm beneath the surface of the earth conceived as the abode of the souls of the dead and, sometimes, as the abode of demons or evil spirits. 

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