Comment by danbruc
You should have a look at the history books. There had not been any significant Jewish population in Palestine for centuries, maybe even more than a millennium, when they started immigrating to Palestine in the late Ottoman period, in the late 19th century, fueled by prosecution and the Zionist movement. They faced resistance in the Ottoman empire and in Mandatory Palestine under British rule after they conquered the Ottoman empire during World War I. The Arabs feared that Jewish immigration would lead to the fulfillment of the Zionist vision, that they would eventually lose their land to the Jews. So there was political resistance like limits on Jewish immigration as well as violent conflicts between Arabs and Jews.
Nonetheless the British continued their support of the Zionist movement as expressed in the Balfour Declaration and allowed - against the will of the local Arab population - more Jews to immigrate to Mandatory Palestine. When the situation became more and more unmanageable for the British, they handed the issue to the United Nations which decided - against the will of the Arab countries - to divide Palestine into two states. This decision caused a civil war in Mandatory Palestine that turned into a war with its neighboring states after Israel declared its independence. During the war Israel ethnically cleansed its territory and displaced hundred thousands of Palestinians.
So Israel went from not existing and Jews owning about ten percent of the land in Mandatory Palestine to encompassing about half of Mandatory Palestine because of the United Nations division plan, then three quarters of Mandatory Palestine which they got under their control in the Arab–Israeli War, to controlling all of Mandatory Palestine after capturing the West Bank and the Gaza strip - and the Sinai Peninsula and the Golan Heights - in the preemptive Six Day War.
Reality is that Israel established itself in Palestine out of nothing with colonialism and violence against the resistance of the Arab population living there and the support of the neighboring countries. I would almost go as far as saying that there is no legitimate basis for the existence of Israel. Sure, there is resolution 181 which was accepted by the United Nations, but is dividing countries against the will of the local population a power that the United Nations should legitimately hold? But now Israel exists and it is probably not going anywhere, past a certain point we can not undo history, even if the status quo arose from historic wrongs. Israel should be honest to itself and try to make good for what it has done to the Palestinians. And if it fails to do so, it should receive all the necessary pressure from the outside.