The land was legally made sovereign as Palestine by the Treaty of San Remo and the Treaty of Sevres, in 1920.
So Palestine is the ONLY legal country there.
The UN has no authority take half of Palestine and give it to Israel.
Here is the 1948 UN partition of Palestine.
You can plainly see the West Bank and Jerusalem is on the Arab side of Palestine, and not Israel.
You will also notice Palestine retained most of the border with Egypt.
The capital of Israel was Tel Aviv until after the 1967 invasion of Jerusalem.