China Stamps - 1990, T158 , Scott 2314 Han Xizai's Night Revels - Full sheet with 4 complete sets - MNH, F-VF (Free Shipping by Great Wall Bookstore) : Water colour block printing, a type of block printing, is employed to reproduce famous works of painting and calligraphy. The art has a long history in China. In 1900, the world's oldest known book printed by engraved blocks came to light from the Dunhuang Grottoes in the form of the 1,100-year-old version of the Prajnaparamita (or Diamond) Sutra produced in A.D. 868 under the Tang Dynasty, now kept in the British Museum in London. During the reign of Tianqi (1621-1627) of the Ming Dynasty, a colour printing process called douhan was perfected for the first time to produce coloured pictures by means of separate blocks, each printing a different colour. The celebrated horizontal scroll "Han Xizai's Party" by the 10th-century artist Gu Hongzhong, measuring over 4 metres long, is noted for its refined portrayal of characters and intricate combination of tones.