The story
From first (adjective) + nation, coined in the late 1970s in place of the word Indian which had become regarded by some as derogatory (though it is still used: see the usage note).
First known use, by meaning
- from late 1970s A community of indigenous peoples of Canada (typically not including the Inuit or Metis), especially one officially recognized by the federal government.
Etymology from Wiktionary, CC BY-SA 4.0.