An example from the US is the Anasazi, a long gone people in the Southwest. When the Navajo came down from (what is now) Canada in the 1400s and 1500s, they referred to the people that already lived there as "ancient enemy" or "anasazi" in the Navajo language. The descendants of the Anasazi, the modern-day pueblo peoples, prefer to call them "Ancestral Puebloan".