The lost tribes were removed from their lands but they were not allowed to leave the empire. You did not want hostile tribes outside your borders. They were taken north, yes-but you have to go north to trace the fertile crescent east into Mesopotamia proper. The "lost tribes" of Semetic peoples blended in with the pagan semetic peoples of the region-thus they vanished--by blending away among the peoples of the empire. No empire-not even the Roman kicks people out of the empire-they move them about inside the empire's borders. The Mongols and Turks did this too. Though I doubt the "Jewish Kurds" are from these lost tribes of Israel their location at the northern arc of the fertile crescent would tend to make that group think they were.