In truth, there are a lot of places on this planet that are not inhabitable.
Yep, approximately 90 % of the Earth's surface would require at least
moderate technology for the survival of humans, and even more if one
includes the regions where humans needed millenia to adapt to the en-
vironment by evolving into subspecies, like the Inuit of the Arctic or the
San of the Kalahari Desert, who would find survival in most other envi-
ronments extremely difficult.
Besides, quite a lot of the currently inhabited surface area was "terra-
formed". The region where I live once was covered by either dense fo-
rests or dangerous swamps, and it took many centuries and lots of man-
power and (low) technology to turn it into an area where more than a
few tiny bands of hunters and gatherers can survive. For a more obvi-
ous example, think of the Netherlands, most of their land is "man made".