Correction: That paragraph should read: Another effect would have been that communication between the believers (not non-believers) and Jews in distant countries like Egypt, Israel (Palestine), Jordan etc would have ceased.
It doesn't take more than a moderately probing look into historical texts, including religious texts like the bible, to know that the ten tribes of Israel were not lost. If one reads Josephus, Jerome, the Prophets in the Old Testament Christian bible and even the books of Tobit and other...