Top 15 Of The Worlds Unsolved Mysteries
The powerful Incan Empire of South America
The powerful Incan Empire of South America thrived between 1535 and 1200 AD. They developed drainage systems and canals to grow their harvests, and constructed rock cities atop steep mountains like Machu Picchu without ever inventing the wheel. Despite their vast accomplishments, the Incan Empire with its 40,000 manned military was no match for 180 Spanish conquistadors equipped with sophisticated weapons. And smallpox.