Paleo-Indians (also spelled Paleoindians) were the first peoples who entered and subsequently inhabited the Americas towards the end of the Late Pleistocene period. The word comes from the prefix paleo-, taken from the Ancient Greek adjective: παλαιός, romanized: palaiós, lit. 'old; ancient', and "Indian", which has been historically used to refer to Indigenous peoples of the Americas. The term Paleo-Indian applies specifically to the lithic period in the Western Hemisphere and is distinct from the term Paleolithic.
Traditional theories suggest that big-animal hunters crossed the Bering Strait from North Asia into the Americas over a land bridge (Beringia). This bridge existed from 45,000 to 12,000 BCE (47,000–14,000 BP). Small isolated groups of hunter-gatherers migrated alongside herds of large herbivores far into Alaska. From c. 16,500 – c. 13,500 BCE (c. 18,500 – c. 15,500 BP), ice-free corridors developed along the Pacific coast and valleys of North America. This allowed land animals, followed by humans, to migrate south into the interior of the continent. The people went on foot or used boats along the coastline. The dates and routes of the peopling of the Americas remain subjects of ongoing debate. There were likely three waves of ancient settlers from the Bering Sea to the American continent.
