Descendants means "downward". It is often used to define the relationship between people or the origin of a family. The word can be used to refer to subsequent generations of the same family: children, grandchildren, great-grandchildren, and so on.
For this reason, we can conclude that the word "descendants" used in the paragraph shown in the above question is intended to refer to family members whose ancestors were Cherokee and who still live in the Appalachians.
