Ten Lost Tribes
Throughout the Hebrew bible Ephraim is often used to refer collectively to the northern kingdom. Ephraim was the leading tribe in the north. It has been claimed that Messiah ben Joseph does not represent the leader of the Ten Lost Tribes and that he is never presented as such. Rather he is presented as the leader of all of Israel. However some later Jewish sources do explicitly call the Messiah ben Joseph the leader of the Ten Lost Tribes.