Battle of Frankenhausen by Werner Tubke. [Photo provided to China Daily]

Yang says Peter Ludwig intended to donate one Picasso piece at first, but the museum hoped the list would include more, so he added three more works by the master. One is an ink painting that Picasso produced with a Chinese paintbrush on a piece of traditional rice paper. The painting used to adorn Irene Ludwig's bedroom.

Yang says Peter Ludwig told his wife that the "painting coming to China would have made Picasso happy".

Also on display is Cubist Still Life with Lemons, a work of 1975 by the late American pop artist Roy Lichtenstein. Influenced by Picasso and Jackson Pollock, Lichtenstein adopted their styles of cubism and abstract expressionism to present a quietness in his collages. Yang says he managed to persuade the Ludwigs to give it to the Chinese museum.

Yang calls the donations "a window" through which more Chinese could understand international art, because other than Soviet realist art, foreign art wasn't available in China at the time.

An exhibition in 1996 caused a sensation, leading to further donations by many established artists, including Chinese artists Wu Guanzhong and Jin Shangyi.

Born in 1925, Peter Ludwig acquired a PhD in art history from Mainz University. He accumulated wealth and eminence with his chocolate-making business. Meanwhile, he also assembled what probably is one of the world's biggest art holdings in private hands. He donated and loaned his collections to museums around the world.