When I was a young man with a serious interest in the indigenous peoples of North America, the accepted theory of their origins was that they came from Siberia across the Bering Land Bridge about 12,500 years ago.
Proposed origin dates before that time were dismissed by academics, but gradually we are coming to have a clearer understanding of a much earlier entry into the Americas. People came from the area of the Bering Sea at different times over thousands of years, possibly on boats that hugged the icy shoreline, definitely on foot across the Land Bridge, and perhaps from much further south, as well.
When they first arrived is now thought to date back 20,000 or more years. How long it took to wander the length of the Americas, from the Bering Sea to the tip of Patagonia, settle vast areas of the two continents, establish thriving civilizations, and eventually populate, if sparsely in some places, the entire land mass of North and South America remains to be determined.
Look at these photographs of the prehistoric paintings just discovered in southern Columbia, which are said to date from more than 12 millennia ago. This cache of art covers miles of rock walls with a highly detailed and sophisticated pictographic representation of a peoples’ life and times.
Think about how long it might have taken to develop a society of such sophistication. One suspects they already had been resident for quite a while. You can read about it here.