The museum, China's imperial palace from 1420 to 1911, also known as the Forbidden City, is home to myriad national treasures.

The salvage campaign saw 13,492 boxes of cultural relics, including artifacts from the Summer Palace and Guozijian (the former imperial academy), embark on a journey to safety.

The relocation work lasted for a few years and the artifacts arrived in cities, including Shanghai and Nanjing in today's Jiangsu province.

However, when the war zone expanded to East China in 1937, they had to be shipped westward again along three routes. Consequently, 9,331 boxes of the cultural relics arrived in Chongqing that year through the middle route. They were secretly stored in three locations in the city, among which 3,694 boxes were put in four warehouses of Anderson Firm, according to Yan Hongbin, deputy director of the Palace Museum.