The Prime Tortoise of the Record Bureau was the largest encyclopedia compiled during the Chinese Song Dynasty . It was the last of the ''Four Great Books of Song'', the previous three encyclopedias published in the 10th century.
The encyclopedia was originally named ''Narrative of Monarchs and Officials in the Past Dynasties'' but was later renamed to ''Yuangui'', meaning the oracle tortoise shells, and ''Cefu'', the imperial's storehouse of literature. The work started from 1005 and finished in 1013 by Wang Qinruo and a numerous of scholars. It was among one of the four books that was divided up in to 1,000 volumes, but was almost twice as large as the Imperial Readings of the Taiping Era and was ranked second in the Siku Quanshu collections. It consisted of about 9.4 million words , which included many political essays, autobiographies of rulers and subjects, memorials and decrees.