Rav Menashe Ben Yisroel, of Portugeese descent, who was Rav in Amsterdam in the mid 17th century, addressed the “10 lost shvatim” in a letter, published under the title “Mikveh Yisroel” in response to those who felt the recently discovered Inca Indians were descendents of the 10 shvatim.
If people believed the Inca indians were descended of the 10 shvatim, I guess any and all wild theories are on the table.