The conventional theory of North American population holds that the first migrants arrived from Asia across an ancient land bridge.
Notes on verification
Well-corroborated as the mainstream/conventional theory across academic, journalistic, and educational sources. This is common knowledge in archaeology and widely taught, though alternative/competing theories (e.g., coastal migration) are increasingly discussed.
Sources
- New Study Refutes Theory of How Humans Populated North America | HISTORY (history.com)
- https://www.scientificamerican.com/article/first-americans-lived-on-bering-land-bridge-for-thousands-of-years/ (scientificamerican.com)
- https://www.sapiens.org/archaeology/bering-land-bridge-first-americans/ (sapiens.org)