Its called geography. And if you read History. Israel was pretty happy with the land it was allocated by the UN, its the Arabs, they said no we will not give any land ( wasn't theirs to give in the first place, basically they wanted to annex Israel/Palestine into their own borders, not that they wanted to keep Palestine an independent country, thats why Syria, Jordan and Egypt all went to war with Israel seeing who could get the most amount of land.
So Israel basically said, oh yeah, then fuck you. Kicked all three of their asses and took over the whole place. If basically these greedy Arabs had STFU that time, there would an internationally recognized country called Palestine today.