That is old theory.RED INDIANS ARE FOREIGNERS IN NORTH AMERICA
The Red Indians who settled in North America millennia ago crossed over from Eurasia via the Isthmus of the Bering Sea. So, by this yardstick, the Red Indians are foreigners in North America. By a quirk of fate, the Red Indians were 250 years or so ago replaced by European settlers. Since the past 1/1.5 centuries, a large number of Africans were brought over into North America and since the past few decades crowds of Asians and Hispanics are settling down in North America and going by the tide of emigrants it's apparent that North Americans of European ancestry may well be outnumbered by non-Europeans in time to come. LOL.
The newer thinking is the native-Americans actually came up from the south. All the recent Paleo evidence since the 1990s supports this.
You need to update your material.