The human history of the Americas begins approximately some twenty thousand years ago with the arrival of nomads who reached the continent, presumably by way of the Bering Strait. These nomads spread not just throughout North America, but the rest of the continent as well, reaching South America roughly fourteen thousand years ago. Archaeological data demonstrates the presence of hunter-gatherers as much as eleven thousand years ago. The rate by which these nomads spread raises the question of whether the only arrivals came from the north.
Evidence also exists that additional arrivals occurred in the south, albeit much later.
One thing that is clear, is that all of them were asiatic in origin. Early settlements began appearing approximately 9000 years ago with the appearance of the first agricultural systems. It is interesting to note that these settlements pre-date those from Central and North America, which lends further credence to the theory that man arrived by more than one route. With the advent of agriculture, the need for constant migration all but disappeared. This led to the establishment of the first societal cultures and the appearance of additional technologies.