The ancient capital of Cahokia and a series of lesser population centers developed in the Mississippi valley in North America between the eighth and fifteenth centuries AD, leaving behind an extraordinarily rich archaeological record. Cahokia's gigantic pyramids, finely crafted artifacts, and dense population mark it as the founding city of the Mississippian civilization, formerly known as the 'mound' builders. As Cahokian ideas and objects were widely sought, a cultural and religious ripple effect spread across the mid-continent and into the South. In its wake, population migrations and...