The phrase "original inhabitants" refers to the people who have lived in a particular place since ancient times or before other groups arrived. They are the first people to settle in an area or land. Full definition
[24] A «quadroon» was defined as «a person who is descended from the full blood original inhabitants of Australia or their full blood descendants but who is only one - fourth of the original full blood»: Native Title Administration Act 1936 (WA), s 2. (humanrights.gov.au)
The tale of Lt. Dunbar's spiritual journey from disenchanted Civil War soldier to revered member of the Great Plains Sioux tribe is one that admirably forgoes demonization of the country's original inhabitants in favor of a compassionate portrait of indigenous people attempting to survive the encroaching hordes of American settlers. (slantmagazine.com)
«Aboriginal» is used in certain other countries to describe original inhabitants of a territory. (practicepro.ca)