Page "Ancient Pueblo Peoples" Paragraph 81

Departures from the expected pattern may occur because of unidentified social or political situations or because of geographic barriers.

In the Southwest, mountain ranges, rivers and, most obviously, the Grand Canyon can be significant barriers for human communities, likely reducing the frequency of contact with other groups.

Current opinion holds that the closer cultural similarity between the Mogollon and Ancient Pueblos and their greater differences from the Hohokam and Patayan is due to both the geography and the variety of climate zones in the Southwest.