Question: Within Four Corners of the United States, which unit of the National Park Service has ruins of the indigenous tribes and is within the boundaries of the Navajo Nation?
Sentence (from "Four Corners"): The Four Corners area is named after the quadripoint at the intersection of approximately 37° north latitude with 109° 03' west longitude, where the boundaries of the four states meet, and are marked by the Four Corners Monument.
Relevant evidence: No