The landmass called Palestine has been under the control of various empires in the past, and not once was a country of Israel established. After WWI and WW2 much of the world was "remapped" - geo-political borders were changed to suit TPTB, not the people.

Prior to WWI the landmass of Palestine was home to multiple ethnicities and faiths -- and always has been. After WWI, the Ottoman empire lost control and ceded the landmass to Great Britain who then issued the Balfour Declaration for the establishment of a "national home for the Jewish people" in Palestine as repayment for the Rothschilds funding the war effort. This was not unusual as Great Britain had a habit of changing borders without regards to the people involved.

Basically, Great Britain did to the landmass of Palestine what is being done to the Western nations today -- mass migration without thought to the existing populations.