When God led His people into the Promised Land, He told them to drive out the enemies that dwelt there; but they failed to do so.
The enemies turned God's people away from Him, and God did to His people what He had planned to do to their enemies.
Some tribes were greatly diminished even before the Assyrian and Babylonian deportations.
But God preserved some of each tribe, and they must all return to that land in preparation for the Second Coming of Christ.