宋书
Initially the Rouran chiefs, according to Chinese sources, having no letters to make records, "counted approximately the number of warriors by using sheep's droppings." Later, they made records using notches on wood. They adopted the Chinese written language, using it to make records and write diplomatic letters, and, with Anagui, started using it to write internal records. There is also evidence of a large number of literate people among the Rouran. This high level of literacy reportedly didn't affect only the elites, but also common people such as cattle-breeders, who were able to use ideograms. In the "Book of Song" there is the story of an educated Rouran "whose knowledge shamed a wise Chinese functionary." Further, it is not excluded that they had their own runic script.