Myths about pre-Columbian North America are as familiar as they are wrong: before Europeans arrived, indigenous peoples of the Americas lived in egalitarian societies subsisting in ideal health and happiness in a vast, untouched wilderness. Or, if you're of a more conservative bent, small bands of indigenous peoples lived on top of a vast sea of riches that they failed to exploit through laziness and ignorance, until Europeans came along. 
 Both views are transparently wrongheaded and entirely Eurocentric, and Charles C. Mann does an excellent job and digging through the history, archaeology, and anthropology of the pre-Columbian Americas to provide readers with a dizzying overview of the depth and breadth of the history of the Americas up until 1491. The research he lays out tells a different story. 
 Indigenous societies were diverse - they were egalitarian and hierarchical, peaceful and aggressive, nomadic and sedentary, literate and illiterate. They were numerous - far more numerous than any Europeans ever witnessed, because the very arrival of the first Europeans sent disease down existing trade arteries of the continent, killing millions before Europeans ever met them. They did not live in a pristine wilderness - almost everywhere they went, they shaped and molded the environment to suit their lifestyles in a way far more savvy than we do today, through fire and agriculture and landscaping and more, and sometimes their mistakes brought their downfall. They had ever-changing histories; dynasties rose and fell, cities were built and destroyed, cultures changed and evolved. 
 It's a wide-ranging, deeply fascinating book that can't help but feel tragic. Much was gained by contact between the two hemispheres, but so much was also lost. Mann highlights all the ways the peoples and achievements of the pre-Columbian Americas live on today and have changed the whole planet, but you can't read a book like this and not wonder what would have happened to the world if disease had not decimated American populations in the centuries following 1492. Thousands of doors closed, never to be opened again. 
 It's worth it, then, to try to recover and remember what we can, and that's where this book and others like it come in. A lot of the book does involve post-Columbian history and politics, but all in the service of trying to understand the earlier past. It's an endeavor that may never really end, or even be conclusive, but Mann makes a compelling case that it's worth trying.