South Asia vs subcontinent

South Asia

name
  • All the countries of the Indian subcontinent (principally India, Pakistan, Bangladesh, Nepal, and Bhutan) and the Indian Ocean (principally Sri Lanka, Maldives) 

subcontinent

name
  • The Indian subcontinent, South Asia. 

noun
  • A large landmass which is either smaller than a continent (such as Greenland), or part of an even larger continent (such as the Indian subcontinent). 

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