From: Jewish Legal Rights and Title to the Land of Israel and Palestine
The legal title of the Jewish People to the mandated territory of Palestine in all its historical parts and dimensions was first recognized under international law on April 24-25, 1920 by a decision taken at the San Remo Peace Conference by the Supreme Council of the Principal Allied Powers to entrust Palestine to Great Britain under the Mandates System for the purpose of establishing a national home for the exclusive benefit of the Jewish People, in accordance with the terms of the Balfour Declaration November 2, 1917.
The Supreme Council of the Allies was made up of the top political leaders and officials of Great Britain, France, Italy, and Japan, and it was they, in their meeting in the Italian resort city, who decided the future fate of all the Asiatic territories which, as a consequence of World War I, had ceased to be under the sovereignty of the Ottoman Turkish Empire which formerly governed them.
These territories included the entire area then called the Fertile Crescent, which originally comprised Palestine, Syria, and Mesopotamia (whose name later became Iraq) as separate countries, before any substantive changes were made to their boundaries. At the San Remo Peace Conference, it was decided that all three countries, whose exact borders had not yet been delineated, would be administered by Mandatories under the newly-created Mandates System, established by the Treaty of Versailles of June 28, 1919. The Mandates System did not come into being until the ratification of this treaty on January 10, 1920. It was established simultaneously with the League of Nations, whose duty it was to supervise the observance of individual mandates through a body called the Permanent Mandates Commission, which reported to the Council of the League of Nations for that purpose. The actual terms of those mandates and the powers exercised by the Mandatory were to be in each case explicitly defined and confirmed by the Council of the League of Nations unless previously agreed upon by the Members of the League, in accordance with Article 22 (8) of the Covenant of the League of Nations.
...The Arabs received the lion's share of the territories that formerly belonged to Turkey. As a result of this munificence, they hold today lands that equal twice the area of the USA...
...When the settlement and division of land was devised at the San Remo Peace Conference, it was clear to all concerned parties, Arab and Jew alike and to all European, American, and Japanese statesmen, that Palestine, within its historical frontiers according to the biblical formula, from Dan to Beersheba, but which still needed to be marked out in a separate agreement, was exclusively reserved for the benefit of the Jewish People all over the world, of which only a fraction then actually lived in the ancient Jewish country. What this obviously meant to one and all was an eventual independent Jewish State in all of the historical territory of Palestine.1.
1.Howard Grief, The Legal Foundation and Borders of Israel under International Law (Jerusalem, Israel: Mazo Publishers, 2008), 702.