Do you mean let Mexico come in and steal Texas back from the U.S.?
The Jewish owned Isreal. They had a home The Jewish people currently own Isreal but if you go back three or four thousand years you will find that the land where Isreal now is has been "owned" by quite a few different people.
Don't mean to offend any Texans here nor to restart any 150+ year old wars.
Bad example, because they DID own it once.
Let's say ....Wisconsin. Mexico never owned it. Let's say the Mexicans decided to take it simply because they chose it. Would we let them have it?