Judah didn't bring in the other nations but God has never abandoned Judah, God has never given up on Judah and now God has gathered them back to Israel like he said.
God did away with the ten tribes of Ephraim called,'' Israel.''
Hosea is about the end of Ephraim.
Hosea 1
For I will no more have mercy upon the house of Israel; but I will utterly take them away.
7But I will have mercy upon the house of Judah, and will save them by the LORD their God, and will not save them by bow, nor by sword, nor by battle, by horses, nor by horsemen.
The Jews may have been punished, but God has never given up on them and they still sit in the seat of authority.
If the sun and moon fall from the sky, you will know when God is done with Judah. They are seemingly countless of scriptures proving the fact that Judah has remained with God all this time and at the coming of the feast of Tabernacles will judge every nation who persecuted them, God will bring the entire earth into a trial on how they treated Judah.
If you go out and help Jews return, Jews that don't even believe in Jesus, God promises you the greatest gift you can receive at this time, and if God blesses you just because you blessed Israel, that alone says everything.
The prodigal son is telling the actual History of Judah and Ephraim.
With every parable there are 3 meanings.
A preacher will get up and speak in General about somebody going away from God and that is a good sermon.
A person who has studied the actual history of Israel knows that the prodigal son is Ephraim, the ten tribes and Judah is the son who has NEVER ABANDONED THE WAYS OF GOD. For 2000 years the Jews have been the only people following the ways of God, and they have been killed for doing this.
There is also the 3rd hidden truth, and that truth is that Jesus came and took two men and made them one man, and you are both.
Ephraim in the flesh and Judah in the spirit.
There is no more female and male because God took two and made them one and so you are a female bride in the flesh which houses the spirit of a Jew.
There is no more slave and no more free man because you are free in Christ, but a slave in this body of flesh to Christ.
There is no more Jew and no more Gentile because Jesus took the two and made them one, in you.