Question: What is this Interior Plain called that native Americans such as the Arapaho lived on (other than the Great Plains)?
Sentence (from "Arapaho"): The Arapaho language, "Heenetiit", is an Algonquian language closely related to Gros Ventre (Ahe/A'ananin), whose people are considered to have separated from the Arapaho at an early time.
Relevant evidence: No