Anthropologists believe that North America's initial inhabitants arrived around 40,000 years ago by traversing the Bering Strait. Some experts feel that by using primitive boats, early man also migrated down the Pacific coast to South America; that debate continues.
There is scientific evidence connecting indigenous Americans to Asian peoples, specifically from the eastern Siberian populations. Indigenous peoples of the Americas have been linked to North Asian populations by linguistic dialects and blood types.
After the last glacial period ended some 12,500 years back, a wide variety of prehistoric cultures developed across the continent, north to south. The development of stone tools was one of the factors instrumental in that successful expansion