When the world speaks of Israel today, they actually are only pointing to the Jews of the "house of Judah" (or old "kingdom of Judah") that God scattered by their 70 years captivity to Babylon by king Nebuchadnezzar, and then their scattering through the countries after that, and then the major scattering (Diaspora) by the Romans in 70 A.D. when the Romans destroyed Jerusalem and the 2nd temple.
And that "house of Judah" that the Jews represent historically were made up of only 3 tribes of old Israel, (tribes of Judah, Benjamin, and Levi), along with a small remnant of the ten northern tribes, and the rest were foreigners that lived in the southern lands of the "house of Judah".
The ten northern tribes of Israel, known as the "house of Israel", and as... "Israel" when God split old Israel starting back at 1 Kings 11, are not Jews. The Jewish historian Josephus (100 A.D.) said the title of 'Jew' is what those of the southern kingdom at Jerusalem-Judea called theirselves, and also the strangers that dwelt among them. Josephus said that title of Jew was derived from the tribe of Judah.
But Israel, after the split of 1 Kings 11, meant the northern ten tribe "kingdom of Israel". God gave Jeroboam of the tribe of Ephraim to be "king of Israel" when He rent the kingdom from Solomon's son Rehoboam.
And the two kingdoms had war against each other. The "kingdom of Judah" in the south and the "kingdom of Israel" in the north, fought against each other. Solomon's son Rehoboam tried to bring the ten tribes back and make one kingdom under the house of David again, but God through His prophet told him not to, because the split was from God Himself (see 1 Kings 12).
Therefore... there can be no real... gathering of Israel, Biblically, until ALL 12 tribes are gathered back to the land, as written in God's Word.
IMPORTANT (especially for brother Judah that believes on Lord Jesus Christ):
We well know the orthodox unbelieving Jews are still waiting for their Messiah to come. They therefore still believe they are under the old covenant, which required sacrifices and a temple. (I'm speaking of the religious Jews in Israel). Bible prophecy for the end of this world we are told will bring those things back in Jerusalem at the end, a new temple, sacrifices, all supporting by the coming false-Messiah to Jerusalem, which Jesus warned us about in His Olivet discourse.
What then does the 1948 gathering of the Jews back to the holy land represent? It represents God's Promise to Judah in Jeremiah 24, where He promised to bring Judah back to the land He gave them, and never remove them again. If the Jews are not removed from the holy land again, then 1948 will have fulfilled that Jeremiah 24 promise from God. And that's it so far, and that excludes the Israel known as the ten tribes.
Today, the scattered ten tribes of Israel are hidden. Neither the Jews, nor the world, knows who they are today, but God knows, and He promised to gather them back with the "house of Judah" to the lands He promised their fathers. That has yet to happen, and won't happen until Lord Jesus Christ returns in our near future.