You mean Tia Tephi. British Israelism (theory = the ten lost tribes migrated north and west to become British/Irish/Scottish/North Americans) thinks so. However interesting as some aspects may be - such as the many "Dans" of the region, like Danube River etc - they lose me in the scriptural "evidence," such as their claim that Jeremiah was father to a princess of Israel, especially considering that God told him specifically that he was not to take a wife (Jer 16:2).
However, I do firmly believe that the ten lost tribes are out there, that God knows who they are (Amos 9:9), and that they will be regathered into Israel as He promised so very many places in scripture. He said he would "save the tents of Judah first" (Zech 12:7), which is what has been happening for about a hundred years now - the house of Judah returning to the land. The house of Israel, however, has yet to be restored and joined with Judah to become one stick (Ez 37).
I've found such stories varying degrees of interesting . . . but have not researched it enough to know what to believe for sure.
Thanks.