15th century mariners
In which John Green teaches you about the beginning of the so-called Age of Discovery. You've probably heard of Christopher Columbus, who "discovered" America in 1492, but what about Vasco da Gama? How about Zheng He? Columbus gets a bad rap from many modern historians, but it turns out he was pretty important as far as the history of the world goes. That said, he wasn't the only pioneer plying the seas in the 1400s.