Mandatory Palestine (Arabic: فلسطين Filasṭīn; Hebrew: פָּלֶשְׂתִּינָה (א"י) Pālēśtīnā (E.Y.), where "E.Y." indicates Ērētz Yīśrā'ēl, the Land of Israel) was a geopolitical entity established between 1920 and 1948 in the region of Palestine under the terms of the League of Nations Mandate for Palestine.

During the First World War (1914–1918), an Arab uprising against Ottoman rule and the British Empire's Egyptian Expeditionary Force under General Edmund Allenby drove the Turks out of the Levant during the Sinai and Palestine Campaign. 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. At the war's end the British and French set up a joint "Occupied Enemy Territory Administration" in what had been Ottoman Syria. The British achieved legitimacy for their continued control by obtaining a mandate from the League of Nations in June 1922. The formal objective of the League of Nations mandate system was to administer parts of the defunct Ottoman Empire, which had been in control of most of the Middle East since the 16th century, "until such time as they are able to stand alone".During the Mandate, the area saw the rise of nationalist movements in both the Jewish and Arab communities. Competing interests of the two populations led to the 1936–1939 Arab revolt in Palestine and the 1944–1948 Jewish insurgency in Mandatory Palestine. After the failure of the Arab population to accept the United Nations Partition Plan for Palestine, the 1947–1949 Palestine war ended with the territory of Mandatory Palestine divided among the State of Israel, the Hashemite Kingdom of Jordan, which annexed territory on the West Bank of the Jordan River, and the Kingdom of Egypt, which established the "All-Palestine Protectorate" in the Gaza Strip.