At the time of World War I the area was ruled by the Turkish Ottoman empire. Turkish control ended when Arab forces backed by Britain drove out the Ottomans.
Britain occupied the region at the end of the war in 1918 and was assigned as the mandatory power by the League of Nations on 25 April 1920.
During this period of change, three key pledges were made.
In 1916 the British Commissioner in Egypt, Sir Henry McMahon, had promised the Arab leadership post-war independence for former Ottoman Arab provinces.
However, at the same time, the secret Sykes-Picot Agreement between war victors, Britain and France, divided the region under their joint control.
Then in 1917, the British Foreign Minister Arthur Balfour committed Britain to work towards "the establishment in Palestine of a national home for the Jewish people", in a letter to leading Zionist Lord Rothschild. It became known as the Balfour Declaration.