Scripture is full of clues that can be fun to find. Here is one.
Romans 9:24-25 “us, whom he also called, not from the Judeans only, but also from the Gentiles? As he says also in Hosea, “I will call them ‘my people,’ which were not my people; and her ‘beloved,’ who was not beloved.”
So here Paul tells us that some “Gentiles” will be “my people” and “beloved”. He sends us back to Hosea to find out who are these Gentiles. Read chapter one of Hosea. These Gentiles are the ten northern tribes of Israel who were divorced by God and sent into exile. They were never to return to the land of Israel, but they would return to God. Notice the wording and the promises at the end of the chapter. The appointed head is Christ. History records that they did return to God upon hearing the Gospel. Our God does not break promises nor give them to “other people”.
Hosea 1:10-11 “Yet the number of the children of Israel will be as the sand of the sea, which can’t be measured or counted; and it will come to pass that, in the place where it was said to them, ‘You are not my people,’ they will be called ‘sons of the living God.’ The children of Judah and the children of Israel will be gathered together, and they will appoint themselves one head, and will go up from the land; for great will be the day of Jezreel.”