The Gathering and Reunion of Israel’s Tribes

Since Israel’s ten northern tribes broke away from the southern tribes of Judah in 924 B.C., then disappeared after being deported to Mesopotamia in 722 B.C., the “two houses of Israel” have never reunited. Still, as David reunited the northern and southern tribes in his day (2 Samuel 5:1–5), so an end-time David—Jehovah’s servant—will do likewise. Isaiah predicts that Jehovah’s servant will “raise up the tribes of Jacob and restore those preserved of Israel” (Isaiah 49:6). At that time, all of Israel’s tribes will return from dispersion to promised lands in an exodus from the four directions of the earth (Isaiah 11:10–16; 43:1–8; 49:9–12, 22; cf. Hosea 3:5).

Ezekiel, too, predicts this: “Behold, I will take the children of Israel from among the heathen where they have gone, and I will gather them on every side and bring them into their own land. And I will make them one nation in the land upon the mountains of Israel, and one king shall be a king to them all. And they shall no more be two nations, neither shall they be divided into two kingdoms any more at all. . . . And they shall dwell in the land I gave Jacob my servant, in which your fathers dwelt; and they shall dwell therein, they and their children and their children’s children forever. And my servant David shall be their prince forever” (Ezekiel 37:21–22, 25).

See more here and here
Study more in-depth