The League of Nations was an international organization founded as a result of the Paris Peace Conference that ended the First World War.
The primary goal of the organization was to maintain world peace and prevent future wars through collective security and disarmament.
The Covenant of the League of Nations was incorporated into the Treaty of Versailles in 1919.
The League of Nations was officially established and came into being when the Covenant took effect on January 10, 1920.
Therefore, the establishment year of the League of Nations is 1920.