Before the invention of paper, words were inscribed on such materials as tortoise shells or bones, metal or stone, bamboo strips or silk. An example is an inscription on a stone drum excavated in the early Tang Dynasty at Tianxing (present-day Baoji City in Shaanxi Province). Carved on 10 faces of the drum is a lively poem about hunting. Studies have dated it to the early years of the State of Qin during the Eastern Zhou Period (770–256 BC). During the Xiping reign period (172–178) of Emperor Ling of the Eastern Han Dynasty a stone pillar was set up in front of the main gate of the National Academy bearing seven inscriptions from the Confucian classics as the standard texts. Cai Yong and some others came up with the idea of engraving the seven volumes of the Confucius classics on stone. Cai himself wrote them on the pillar in the clerical-script style. The History of the Later Han Dynasty * Biography of Cai Yong reads: During the fourth year of the Xiping reign period, Cai Yong “pleaded with the Ling emperor to allow him to proofread and correct the errors found in the ‘Six Confucius Classics,’ and the latter gave him his consent. Cai then inscribed the Confucian texts on a stone tablet with ink of cinnabar and hired a mason to engrave them on it. After it was finished, he had the tablet erected in front of the National Academy’s main gate. Confucian scholars and students of the later generations all used the engraved texts as the standard. When the tablet was first erected, viewers and those who wanted to copy the texts came by more than a thousand chariot-loads a day, so much so that they jammed the streets all around.” 1 Jian-du was made of either bamboo or wood whittled and pared down to slips. Bamboo slips were called “jian” and wood “du.” Texts were written on them with a brush pen soaked with ink. A number of slips were strung into a book known as “ce.” Large amounts of jian-du ce have been excavated in Dunhuang and Juyan, as well as Shangcha of Hunan, Jiangling of Hubei and Linyi of Shandong. Before the invention of paper, most of the ancient classics had been recorded on bamboo or wood slips and survive to this day.