The museum signed a cooperation agreement with China Post to better share resources and develop more products from the cultural relics in 2014.

Bathing Horses, a signature painting by 13th-century artist Zhao Mengfu, was the first masterpiece to be printed on stamps.

Last year, the two organizations jointly released stamps inspired by the 11-meter-long rolling-scroll painting A Panorama of Rivers and Mountains by Song Dynasty (960-1279) artist Wang Ximeng, which is among the most prominent works in Chinese fine-art history. The piece was printed on nine stamps in a row. It is also the first set of stamps to completely display an ancient scroll painting.

According to Li, images of the Forbidden City and some of the museum's cultural relics have been depicted on postage stamps many times since New China was founded in 1949.

"Stamps are like a country's business card," Li says. "They enable people to get a closer look at the finest works in our traditional culture."

Shan says that the stamps are also a kind of precious heritage of the Palace Museum.