Opening paragraph...........

The stories began a thousand years ago, but as stories they
hardly survive at all.  In Chaco Canyon, in what we now call
New Mexico, the remains of massive pueblos dominate the
landscape.  In the greater Mississippi Valley, what seem small
natural hills are in fact massive earthen mounds raised a
millennium ago by human hands.  Who built these places and
why are questions that remain shrouded in mystery.  The
structures in Chaco Canyon are attributed to those called
Anasazi (a Navajo slur meaning "Ancient Enemies") or, more
neutrally, "Ancestral Puebloans."  The creators of the eastern
earthworks are known only by the popular term
"Moundbuilders" or by the scholar's label "Mississippians." 
Fragmentary memories of these people survive in Native
American stories about past migrations and conflicts, but the
lack of clear references to the creators of such dramatic
structures is striking.   It is almost as is some trauma led to
cultural amnesia among those who came later.  Traditions
recited at Acoma Pueblo in the early twentieth century speak
of long-ago folk who were unhappy in their homes and
migrated to the south.  "It is not known how far they went,"
the story says, "but finally they stopped at a place where they
went through the ceremony of forgetting....and left their
sickness and trouble behind.

Daniel K. Richter,  Before the Revolution: America's Ancient Pasts