The simple point to be inferred from this whole issue of the Ten Lost Tribes is that the Jews are not all of Israel. God’s purpose is to let the 10 tribes which were separated in King Rehoboam’s time, to become lost to the world and the two tribes of Judah to remain visible. Deuteronomy 32:26; 2 Chronicles 10:19; Jeremiah 29:18
They both have specific tasks to fulfil, during this period of dispersion, the Church age.
Perhaps one way to identify the other Israelite tribes, besides those Jews already known, is to look for those who fear, acknowledge and love the Creator God, live by His laws and produce the fruit of good works. James 2:24.
The Caucasian, Western nations (people groups) have been identified by the historical, linguistic, archaeological and genetic research, as having a majority of descendants of Israel/Jacob. They are also the Christian nations, so this is another proof.
According to some records, at least one tribe went eastwards and I think that South Korea, because of it’s amazing Christian awakening, has quite probably, Israelite origins.
Bible prophecy clearly says that all Israel will be gathered before Jesus returns and Gods promises to the Patriarchs must be kept. Ezekiel 20:34-38 Genesis 17:6-8
Malachi 3:16-18 Then those who feared the Lord, talked together – the Lord listened.
A record was written of those who feared Him and respected His Name. They will be Mine, says the Lord of Hosts, My own possession for the Day that I appoint, I will spare them. Once more you will see the difference between those who serve God and the wicked apostate peoples.
Malachi 4:1 The Day comes; burning like a furnace, all the arrogant evildoers will be as stubble, they will be destroyed in a fiery blaze.
Malachi 4:2-3 But you, who fear My name, the sun of righteousness will rise with healing in its wings and you will break loose, like calves released from a stall.
Malachi 4:3 On the Day that I take action, you will tread down the wicked, they will be as ashes under your feet.
Malachi 4:4-6 Remember the Laws given to Moses, keep all My commandments given to Israel at Sinai. Look; I will send you Elijah before the Day of the Lord. He will reconcile families and preserve the Land from the wrath of the Lord.
Reference: Revised English Bible, some verses abridged.
The Prophetic Word 