The continents that are now called North and South America first received their name from a 15th-century Italian merchant and explorer named Amerigo Vespucci. However, the history of the Americas goes back much further than the late 1400s and European colonization. The continents of the "New World" were all inhabited by a litany of tribes and civilizations that predate the arrival of Europeans by thousands of years. However, even today, more information is emerging that could put once commonly held theories about human migration in the Americas into jeopardy. So, who were the first people to arrive in the Americas?