Richard got the basics down for you.

After WWII, The United Nations Special Commission on Palestine recommended that Palestine be divided into an Arab state and a Jewish state. The commission called for Jerusalem to be put under international administration The UN General Assembly adopted this plan on Nov. 29, 1947, owing to support of both the US and the Soviet Union, and in particular, the personal support of US President Harry S. Truman.

As you can imagine, the Jews loved this plan; the Arabs not so much.

On May 14, 1948, the British left; Israel declared they were an independent state, and the modern wars began. Israel and the Palestinians have been fighting ever since.