if Germans from the 1850s migrated to the US, and lived in a German village, and only had offspring with other Germans, then their offspring would be the same as the Germans in Germany. Just because they are culturally different, or perceive a different citizenship, doesn't change that. Same with Saul. By his own declaration, he is an Israelite from the tribe of Benjamin. He knows enough about his genealogy to know that. I also know this must be true or God would have never selected him, because God didn't go from a Israel-Only racist in 450 BC when brought Ezra back from Persia to a hippy free loving race mixer when He sent Saul.