@SummerFeverVenice
The Arab League was formed in Cairo on 22 March 1945 with six members: Egypt, Iraq, Transjordan (renamed Jordan after independence in 1946), Lebanon, Saudi Arabia, and Syria. Yemen joined on 5 May 1945.
Since its formation the Arab League has promoted the Palestinian Arab cause in the Israeli–Palestinian conflict, including by imposing the Arab League boycott of Israel.
The Arab League opposed the United Nations Partition Plan for Palestine in 1947. On 15 May 1948, the then seven Arab League members coordinated an invasion of what was by then the former British Mandate, marking the start of the 1948 Arab–Israeli War.
To rewind a bit - At the Conference of San Remo, (April 19–26, 1920), international meeting convened at San Remo, on the Italian Riviera, to decide the future of the former territories of the Ottoman Turkish Empire, one of the defeated Central Powers in World War I; it was attended by the prime ministers of Great Britain, France, and Italy, and representatives of Japan, Greece, and Belgium.
The conference approved the final framework of a peace treaty with Turkey which was later signed at Sèvres, on Aug. 10, 1920. The Treaty of Sèvres abolished the Ottoman Empire, obliged Turkey to renounce all rights over Arab Asia and North Africa, and provided for an independent Armenia, for an autonomous Kurdistan, and for a Greek presence in eastern Thrace and on the Anatolian west coast, as well as Greek control over the Aegean islands commanding the Dardanelles.
Rejected by the new Turkish nationalist regime, the Treaty of Sèvres was replaced in 1923 by the Treaty of Lausanne, which voided previous Allied demands for Kurdish autonomy and Armenian independence but did otherwise recognize Turkey’s current boundaries.
During the Conference of San Remo, two “A” mandates were created out of the old Ottoman province of Syria: the northern half (Syria and Lebanon) was mandated to France, the southern half (Palestine) to Great Britain.
The province of Mesopotamia (Iraq) was also mandated to Great Britain. Under the terms of an “A” mandate the individual countries were deemed independent but subject to a mandatory power until they reached political maturity.
The "mandate system" was created in the aftermath of World War I to resolve the question of jurisdiction over the colonial territories detached from Germany and the Ottoman Empire.
Article 119 of the Versailles required Germany to renounce sovereignty over former colonies and Article 22 converted the territories into League of Nations mandates under the control of Allied states.
Mandatory Palestine was designated as a Class A Mandate, based on its social, political, and economic development. This classification was reserved for post-war mandates with the highest capacity for self-governance. All Class A mandates other than mandatory Palestine had gained independence by 1946.