...hid it, really, when they moved from Black Mountain NC up north to Pennsylvania.

It wasn't considered by them to be a welcoming attribute in their new town, and they relied on a common association of their dark skin with whatever African heritage they had. It was actually more socially acceptable to be black than Indian, in that time for them, so any ID died with them, perpetuated only by a few surviving stories of the past from a dwindling number of offspring.

Thing is, in Black Mountain, there was a history of blacks in flight from slavery, and Indians on the run, as well taking refuge there for generations after the periods of enslavement, persecution, and unrest. Many tribes intermingled with other tribes, as well with populations of Asians who were effectively chased off and abandoned after the railroads were finished.

I don't think there's enough accounting for just how much our nation is truly a 'melting pot' of ethnicities and origins.