By the late 1800s, most scholars had accepted a theory that people first migrated to the Americas from Asia across a "Bering Strait Land Bridge," and some believed this had occurred 4,000 to 6,000 years ago. The "land bridge" (a vast area now usually called Beringia) became available several times in the last 70,000 years due to huge drops in sea level during the Ice Age.

Since the late 1950s, scholars have known through radiocarbon dating that people have been in the Americas for at least 11,500 years. The most recent research suggests that the times of entry were likely far earlier than 11,500 years ago.

"The non-Western, tribal equivalent of science is the oral tradition, teachings that have been passed down from one generation to the next over uncounted centuries....[It] explains the nature of the physical world as people have experienced it and the important events of their historical journey."
- Vine Deloria, Jr., Standing Rock Sioux, Professor of History and American Indian Studies, University of Colorado, 1997

Native American groups have ancient accounts of their origins. Some are very detailed, with descriptions of their migrations through time across the land and of events that occurred, while others are metaphoric and are based on concepts of time and nature different from those of Euro-American culture. These oral histories show an intensely close relationship through time with the land. While some scholars may debate the accuracy of such accounts, these oral traditions are, for Native Americans and other scholars, as valid as Western accounts, and are potentially important evidence in NAGPRA claims.

Many archaeologists have used Native American oral traditions in their own research to help interpret sites and establish cultural affiliation.

"Oral histories can be shown to conform to...archaeological evidence to an extent not easily attributed to the construction of an after-the-fact explanation for the presence of numerous ruins throughout the region. These histories reflect direct knowledge of events in prehistoric Arizona."
- Lynn S. Teague, Archaeologist, Arizona State Museum, 1993

"A small group of anthropologists have now allowed that Indians, instead of marching four abreast over the mythical Bering land bridge, might have come by boat...from the Asian continent to North America."
- Vine Deloria, Jr., Standing Rock Sioux, Professor of History and American Indian Studies, University of Colorado, 1997

Several recent discoveries have created new ideas about the arrival of people to the Americas. One of the most important is an archaeological site in Chile — Monte Verde — which is at least 12,500 years old; another part of the site might be 33,000 years old. Because of its location 10,000 miles south of Alaska and the Bering Strait, Monte Verde means that people may have arrived in the Americas much earlier than 12,500 years ago. Such discoveries have sparked discussions about the possibility that people traveled from Asia to North America along the coast, perhaps using boats.

New genetic research suggests that Native Americans share a common ancestor with the native peoples who now occupy south-central Asia. Some anthropologists have noted that the narrow, elongated skull shape of Kennewick Man — and other features traditionally called "Caucasoid" — are shared by several early populations in Asia and the Pacific. Based on this information, many scholars believe that it would be "far-fetched" at this point to suggest that Kennewick Man came from Europe.