That British Israelism crap is analogous, and in some cases directly descended from it. 25 or 30 years ago, here in Michigan, there was a cult which its leader named the “Black Hebrew Israelite Jews”, and claimed that the Old Testament Hebrews were actually black African.
The guy I encountered here was off on a rant about how the American Civil War was caused by the Rothschilds, who, incidentially, aren't real Jews. And it went on from there.