The earliest known calligraphy collection in China, recently bought by the Shanghai Museum for US$4.5 million, went on display yesterday. The works date to 992AD during the Northern Song dynasty. They were bought by the museum and the Shanghai municipal government in April from Robert Ellsworth, an American collector who bought the works in 1995 at an auction in Hong Kong for US$300,000. The ancient works are all rubbings - a traditional technique of forming prints by rubbing a paper placed on an engraved surface. Wang Qingzheng, deputy curator of the museum, said the collection was an immensely valuable example of China's cultural heritage. If not returned to the mainland, 'we would have let down the country's future generations', he said. The works record a long history of Chinese calligraphy and as a result, are more valuable in terms of historical reference than a single vase or painting, Mr Wang said. The original collection comprised 10 volumes, which included the works of 108 emperors, senior officials and calligraphers. Only four volumes have survived. Three are rubbings produced from the calligraphy of Wang Xizhi, who is known as the 'saint of calligraphy', and the fourth is based on work by senior officials from the Tang dynasty. The museum is to publish 1,000 prints of the works, priced at 6,000 yuan (HK$5,600) each. The exhibition will run until the end of next month.