sentences:  The articles in the museum consisted of the valuables of the former Imperial family.In 1931, shortly after the Mukden Incident Generalissimo Chiang Kai-shek's Nationalist Government ordered the museum to make preparations to evacuate its most valuable pieces out of the city to prevent them from falling into the hands of the Imperial Japanese Army.As a result, from 6 February to 15 May 1933, the Palace Museum's 13,491 crates and 6,066 crates of objects from the Exhibition Office of Ancient Artifacts, the Summer Palace and the Imperial Hanlin Academy were moved in five groups to Shanghai.