early cultures were present in the americas before the arrival of
Pre-Columbian era While the phrase "pre-Columbian era" literally refers only to the time preceding Christopher Columbus's voyages of 1492, in practice the phrase is usually used to denote the entire history of indigenous Americas cultures until those cultures were exterminated, diminished, or extensively altered by Europeans, even if this happened decades or centuries after Columbus's first landing. For this reason the alternative terms of Precontact Americas, Pre-Colonial Americas or Prehistoric Americas are also in use. In areas of Latin America the term usually used is Pre-Hispanic.
History of North America The specifics of Paleo-Indians' migration to and throughout the Americas, including the exact dates and routes traveled, are subject to ongoing research and discussion.[1] For years, the traditional theory has been that these early migrants moved into the Beringia land bridge between eastern Siberia and present-day Alaska around 40,000 â€“ 17,000 years ago, when sea levels were significantly lowered due to the Quaternary glaciation.[1][4] These people are believed to have followed herds of now-extinct pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets.[5] Another route proposed is that, either on foot or using primitive boats, they migrated down the Pacific coast to South America.[6] Evidence of the latter would since have been covered by a sea level rise of hundreds of meters following the last ice age.[7]