Dan, I'm going to offer 2 quotes from Joseph Klausner and then provide the source text from Syriac Baruch and IV Ezra. I'm just curious: what are your thoughts about this ancient Jewish belief that the lost tribes intermingled with Gentiles so that their original identity was completely lost?
Here are the excerpts with source text:
"Resurrection will be attained both by those who were originally righteous but later 'mingled themselves with the seed of mingled peoples,' and by those who were originally wicked but later joined with the people of Israel, that is to say, the Ten Tribes and the righteous proselytes (42:1-5)," Klausner, The Messianic Idea in Israel, pg. 347
"IV Ezra emphasizes with all force the expectation of the attack of the nations (the war of Gog and Magog) in the Days of the Messiah, and in connexion with this the ingathering of the exiles and the return of the Ten Tribes," ibid pg. 363