The central point of Charles Mann's book, 1491: New Revelations of the Americas Before Columbus, was that the native people in North and South America had developed extremely sophisticated culture long before the arrival of Europeans. Mann, a journalist who first became interested in this issue when on assignment in Mexico, attempts to address two issues in this book, the complexity and sophistication of early civilizations in the Americas and the reasons why this complexity is underestimated in the popular imagination.
For him, the crucial dates are the arrivals of the first Europeans in the Americas in the late fifteenth and early sixteenth centuries. The native population had no resistance to the epidemic diseases brought by the Europeans, especially smallpox, resulting in a catastrophic death rate which Mann estimates as affecting approximately 95 percent of the native populations. This caused the collapse of native civilizations in short order, meaning that many of the accounts on which images of native populations are based are not of the civilizations at their peaks, but of them after a devastating collapse.
The main part of the book covers in some detail the complexity and achievements of three early American cultures, the Incan, the Mayan, and the eastern tribes of North America.