<P> According to archaeological and genetic evidence, North and South America were the last continents in the world with human habitation . During the Wisconsin glaciation, 50,000--17,000 years ago, falling sea levels allowed people to move across the Bering land bridge that joined Siberia to north west North America (Alaska). Alaska was ice - free because of low snowfall, allowing a small population to exist . The Laurentide ice sheet covered most of Canada, blocking nomadic inhabitants and confining them to Alaska (East Beringia) for thousands of years . </P> <P> Aboriginal genetic studies suggest that the first inhabitants of the Americas share a single ancestral population, one that developed in isolation, conjectured to be Beringia . The isolation of these peoples in Beringia might have lasted 10,000--20,000 years . Around 16,500 years ago, the glaciers began melting, allowing people to move south and east into Canada and beyond . </P> <P> The first inhabitants of North America arrived in Canada at least 15,000 years ago, though increasing evidence suggests an even earlier arrival . It is believed the inhabitants entered the Americas pursuing Pleistocene mammals such as the giant beaver, steppe wisent, musk ox, mastodons, woolly mammoths and ancient reindeer (early caribou). One route hypothesized is that people walked south by way of an ice - free corridor on the east side of the Rocky Mountains, and then fanned out across North America before continuing on to South America . The other conjectured route is that they migrated, either on foot or using primitive boats, down the Pacific Coast to the tip of South America, and then crossed the Rockies and Andes . Evidence of the latter has been covered by a sea level rise of hundreds of metres following the last ice age . </P> <P> The Old Crow Flats and basin was one of the areas in Canada untouched by glaciations during the Pleistocene Ice ages, thus it served as a pathway and refuge for ice age plants and animals . The area holds evidence of early human habitation in Canada dating from about 12,000 . Fossils from the area include some never accounted for in North America, such as hyenas and large camels . Bluefish Caves is an archaeological site in Yukon, Canada from which a specimen of apparently human - worked mammoth bone has been radiocarbon dated to 12,000 years ago . </P>

When did the first nations arrive in canada