There are various groups that believe white Americans (real Americans, that is, whatever that means) are descended from the lost tribes of Israel. Given the remarkably mixed nature of white American ancestry, this is a truly idiotic notion.
For some reason that I find very obscure, they tend to be racist and/or neo-nazi, harping on about “mud-people” and the like.
A relative was involved with such a group for a while, which is how I became aware of them.
He got better. :)
I believe those are the Herbert Armstrong groups.