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Many people balk at the idea that North America had any substantial civilization before 1492, the moment that it is customarily believed this continent switched from prehistory to history. I remember being on a National Public Radio talk show and a caller accused me of making an unwarranted upgrade when I said there was civilization in the ancient Southwest.
A thousand years ago, people in the Southwest had not invented the wheel, had no armies and relied on stone tools, which has marked them as uncivilized. They are imagined as cavemen. But the recent discovery of chocolate in a broken jar from pre-Columbian New Mexico might be enough to change that kind of thinking.
North Americans in the early centuries AD were gathering into population centers, dabbling in metallurgy and domesticating animals such as dogs and turkeys. Public works were going full swing. Beneath the modern city of Phoenix you will find remains of several hundred miles of mathematically engineered irrigation canals that once fed a hydraulic society on a par with early Mesopotamia.