borderland vs outback

borderland

noun
  • Land near a border; marches. 

outback

noun
  • The most remote and desolate areas of Australia; the desert and areas too arid for growing crops. 

adv
  • To or towards the most remote and desolate areas of Australia. 

verb
  • To travel or stay in the outback 

adj
  • Characteristic of the most remote and desolate areas of Australia; very remote from urban areas. 

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