You don't understand what happened. Or maybe you are just going to poo poo the whole thing because it does not fit Israel's BS.
After WWI, the allied powers decided to create five new states in that area. They defined the international borders and named each one. Lebanon, Syria, Iraq, Transjordan, and Palestine. The Treaty of Lausanne transferred the territory to these new states and the people became nationals of their respective state. Local laws granted citizenship to these people.
The UN has stated that the Palestinian people in Palestine (no mention of a government or state) have the standard list if inalienable rights.
Definition of inalienable
: incapable of being alienated, surrendered, or transferred
incapable of being alienated, surrendered, or transferred… See the full definition
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