The Shandong Problem (simplified Chinese: 山东问题; traditional Chinese: 山東問題; pinyin: Shāndōng wèntí) refers to the dispute over Article 156 of the Treaty of Versailles in 1919, which dealt with the concession of the Shandong Peninsula.
During the First World War, China supported the Allies on condition that the Kiautschou Bay concession, Imperial Germany's concession on the Shandong peninsula, would be returned to China. However, in 1915, China, forced by Japanese ultimatum, reluctantly agreed to a reduced set of "Thirteen Demands" from Japan's original Twenty-One Demands which, among other things, acknowledged Japanese control of former German holdings. Britain and France promised Japan it could keep these holdings. In late 1918, China reaffirmed the transfer to Germany and accepted payments from Japan. Article 156 in 1919 officially transferred the concessions in Shandong to Japan rather than returning sovereign authority to China.
Despite its formal agreement to Japan's terms (in 1915 and 1918), China at Paris in 1919 now denounced the transfer of German holdings, and won the strong support of President Wilson. The Chinese ambassador to France, Wellington Koo, stated that China could never relinquish Shandong, which was the birthplace of Confucius, the central Chinese philosopher, as much as Christians could not concede Jerusalem. He demanded the promised return of sovereignty over Shandong, to no avail. Japan was adamant and prevailed. Chinese popular outrage over this provision led to demonstrations and a cultural movement known as the May Fourth Movement and influenced Wellington Koo not to sign the treaty.