"Israel" and "Judah"
One of the most misunderstood subjects of Bible study involves the total political division of "Israel" and "Judah" that occurred at the time of King Rehoboam. Before then, all twelve tribes of Israelites were a united kingdom through the reigns of David and Solomon, but after Solomon's death they split into two completely separate and independent kingdoms - the southern kingdom of "Judah," consisting of the tribes of Judah and Benjamin, with part of Levi since the Levites were distributed among the other tribes (1 Kings 12:23) with their capital at Jerusalem, and the northern kingdom of "Israel," consisting of the other ten tribes (Reuben, Simeon, Dan, Naphtali, Gad, Asher, Issachar, Zebulun, Ephraim and Manasseh (Joseph was divided into Ephraim and Manasseh), with part of Levi since the Levites were distributed among the other tribes), with their capital up in Samaria.
Israel and Judah were never united again (see Kings of Israel and Judah). Surprisingly, they even fought wars against each other from time to time (see Jews At War With Israel). A very important fact that many do not realize is that Judah, that is, the Jewish people of today, are only one of the tribes of Israel - while all Jews are Israelites, not all Israelites are Jews.
Because of their forsaking of Him, God permitted the two kingdoms to be destroyed. First, the northern kingdom of Israel was gradually conquered by the Assyrians (see Ancient Empires - Assyria), and by 721 B.C. they had practically all been taken into exile to Assyria (2 Kings 17:1-23). The vast majority of them never returned, and have become known as the "Lost Ten Tribes of Israel."
Then, about 135 years later, by 586 B.C., the southern kingdom of Judah was completely conquered by the Babylonians (see Why Babylon?), and the people of Judah were taken into captivity to Babylon. The original Temple of God in Jerusalem was destroyed at that time (see Temples). The people of the southern kingdom of Judah however did return after the Babylonians fell to the Persians (see Ancient Empires - Persia), and their descendants have become the Jewish people of today - but that return in the time of Nehemiah, or the founding of the modern state of Israel in 1948, were not the fulfillment of the many prophecies dealing with the future (as the context of the prophecies clearly show) gathering of all of Israel, Israel and Judah.
The Coming Gathering of Israel and Judah
There are many Scriptures which describe, in great detail, the future gathering of Israel and Judah. Examples:
"Behold, I will bring them from the north country, and gather them from the farthest parts of the earth, among them the blind and the lame, the woman with child and her who is in travail, together; a great company, they shall return here. With weeping they shall come, and with consolations I will lead them back, I will make them walk by brooks of water, in a straight path in which they shall not stumble; for I am a father to Israel, and Ephraim is my first-born. Hear the word of The Lord, O nations, and declare it in the coastlands afar off; say, 'He who scattered Israel will gather him, and will keep him as a shepherd keeps his flock.'" (Jeremiah 31:8-10 RSV)
"Thus says The Lord God: Behold, I am about to take the stick of Joseph, which is in the hand of Ephraim, and the tribes of Israel associated with him; and I will join with it the stick of Judah, and make them one stick, that they may be one in my hand. When the sticks on which you write are in your hand before their eyes, then say to them, Thus says The Lord God: Behold, I will take the people of Israel from the nations among which they have gone, and will gather them from all sides, and bring them to their own land; and I will make them one nation in the land, upon the mountains of Israel; and one king shall be king over them all; and they shall be no longer two nations, and no longer divided into two kingdoms. They shall not defile themselves any more with their idols and their detestable things, or with any of their transgressions; but I will save them from all the backslidings in which they have sinned, and will cleanse them; and they shall be My people, and I will be their God." (Ezekiel 37:19-23 RSV)
Fact Finder: Did God say that the people of Israel would be sifted (i.e. distributed) among all nations?