I’ve read that the largest group of unintergrated White people left in the world today are those living in the Appalachian Mountains.
Possibly, although that observation may fail to take into account the frequent intermarriage with Cherokees and other Native Americans (my wife has enough Cherokee to qualify for tribal membership, should she ever desire to do so).
I don’t understand what you mean by “unintegrated”???
Quite a lot of Appalachian folk have Ani-Yun-Wiya (Tsalagi or Cherokee) bloodlines intermingled with English, Scots/Irish, German, Dutch. etc....Often there is also African in there as well...though not as much as the early Appalachians couldn’t afford slaves even if they had wanted them.
I was told by an english professor at the University of Tennessee that the mountain dialect was as close to true “Olde English” as America had to offer...(BTW, I am born and raised in the mountains and my ancestry is Ani-Yun-Wiya and Scots/Irish...)