The Lost Ten Tribes merged with the people of Gomer otherwise known as the Cimmerians. Strabo tells us this. They moved to the West. Welsh tradition links their ancestors to Gomer and the Cimmerians.
In fact the adjective for "something that is Welsh" is Cymric from Cymmerians
https://en.wikipedia.org/wiki/CymricThe Ten Tribes were exiled to different portions of the Assyrian Empire. They became associated with a federation of other peoples associated with Gomer son of Japhet.
This is reflected in the first chapter of the Book of Hosea where the Ten Tribes in their places of exile are described as children of a woman named Gomer. The peoples of Gomer are otherwise known as the Cimmerians and Scythians.
They first appeared in the Middle East but shortly afterwards appear in the West. This was a result of the transference of the Ten Tribes to western areas.
Homer (possibly written in the 400s BCE) placed these same Cimmerians (Odyssey, Book 11, 14) as living in the Atlantic Oceanus, in a land of fog and darkness, at the edge of the world and the entrance of Hades. This has been understood as referring to Britain. You know, were Celts lived.
Hecateus of Abdera (ca. 350-300 BCE) mentioned a Cimmerian city amongst the Hyperboreans in the north of Europe.
http://hebrewnations.com/articles/16/hesperides/hesperides2.html#a11Josephus placed Gomer and the "Gomerites" in Anatolian Galatia: "For Gomer founded those whom the Greeks now call Galatians, but were then called Gomerites."
