late edit: DISCLAIMER: The pictured map is not actually a representation of the territories before colonisation. It's a hypothetical map of what countries there might have been had the continent not been colonised, thus all the names and borders are fictional and have never existed.
For good actual maps, check out native-land.ca.
Right, Warren claimed Cherokee ancestry, not tribal membership. A story was passed down in her family and the DNA test results are in line with that story. She learned about the culture, visited the lands, and even published a cringey cookbook. By all accounts, her beliefs about her heritage were sincere and plausible, if embarrassing.