 Approximately 600 "leishu" were compiled from the early third century until the eighteenth century, of which 200 have survived.The largest "leishu" ever compiled was the 1408 "Yongle Encyclopedia", containing 370 million Chinese characters, and the largest ever printed was the "Gujin Tushu Jicheng", containing 100 million characters and 852,408 pages.The genre first appeared in the early third century.