God promised the land to Abraham. God gave the Jews Israel. God is the leader of all people so if he gave the land to Abraham the jews of Israel should get it. And in Genesis 12:1-3, the Lord says to Abraham, “Go from your country and your kindred and your father's house to the land that I will show you. And I will make of you a great nation, and I will bless you and make your name great, so that you will be a blessing. I will bless those who bless you, and him who dishonors you I will curse, and in you all the families of the earth shall be blessed.” This blessing included land that, at the time the promise was made, belonged to other people.

The Jewish people settled and developed the land. As far back as records show, the Jewish people occupied the land. The jews settled in the land so I think that since the jews settled there it should be there's until it gets ruled over or sold. And because the land was occupied the land. Also, The Land of Israel/Palestine again became an actor in world affairs and a focus of wide interest with Zionism’s successful effort to ensure for Jews a place among the nations of the world with a Jewish state according to the Jewish Virtual library