The source of the lyrics is based upon a Native American tribal oral history lesson.
Truth is, the story was never actually written, but passed along from one generation to the next.
But if one is diligent and seeks answers, one will find one of the oral histories of the Native Americans which tell of their encounters with giants. One of the stories of a particular tribe speaks of a kingdom on a mountain as the natives were migrating from the west.
But now you must dig deeper into the story to reveal the hints of truth of what really happened in history. It is said, "history is written by the victor". When one comes to the realization of what really happened, one word comes to mind as history goes, and it's "Karma".
What the immigrating Europeans had done to the Native Americans, the Native Americans may have certainly done to those who once lived here before them. But history goes incomprehensibly farther back in time than recorded history, much farther back than we can imagine and what we were mislead to believe. Billions of years is a very, very, long time and the face of this world has changed before and since Pangea.