Mandatory Palestine was a geopolitical entity established between 1920 and 1948 in the region of Palestine under the terms of the "Mandate for Palestine", which was a League of Nations mandate for British administration of the territories of Palestine and Transjordan, both of which had been conceded by the Ottoman Empire following the end of World War I.
The United Kingdom had agreed in the McMahon–Hussein Correspondence that it would honour Arab independence if they revolted against the Ottomans, but the two sides had different interpretations of this agreement, and in the end, the UK and France divided up the area under the Sykes–Picot Agreement—an act of betrayal in the eyes of the Arabs. Further complicating the issue was the Balfour Declaration of 1917, promising British support for a Jewish "national home" in Palestine.
During the British Mandate period the area experienced the ascent of two major nationalist movements, one among the Jews and the other among the Palestinian Arabs. The competing national interests of the two populations against each other and against the governing British authorities matured into the Arab Revolt of 1936–1939 and the Jewish insurgency in Mandatory Palestine, before culminating in the 1947–1949 Palestine war. This led to the establishment of the 1949 cease-fire agreement, with partition of the former Mandatory Palestine between the newborn state of Israel with a Jewish majority, the Arab West Bank annexed by the Jordanian Kingdom and the Arab All-Palestine Protectorate in the Gaza Strip under Egypt.