Why did the Dutch come to the North American shores 400 years ago? Was it wanderlust, expansionist policies, or simply money? The earliest western explorers were the Vikings who, in the 1100s, were able to sail beyond Iceland and Greenland to Newfoundland, because they did so during the Medieval Warm Period. English explorer Henry Hudson, on the other hand, could not find a northern passage to China because the early 1600s were the coldest part of the Little Ice Age and the northern seas were frozen over (Figure 1).