Don’t think that Christian Identity is a new thing and don’t think that there is no scriptural backing (like the Mormons, Jehovah Witness and others). Here is a book that was written in 1878. Of course, the early Christians knew they were the Israelites and you’ll read that in the New Testament.
47 Identifications of the Anglo-Saxons with the Lost Ten Tribes of Israel. Founded upon 500 scripture proofs. By Edward Hine, 1878. 308 page PDF