This presentation will commence with an introduction of newly discovered sources and eamine them in order to identify the different cultures of computation they exhibit. These documents are commentaries made by Jia Gongyan賈公彥(7th century) on Confucian canons. By relying on these sources, we shall see there existed at least two cultures of mathematics in 7th century China. Furthermore, in order to cast more light on these sources, I shall compare them to the mathematical books handed down through the written tradition. Li Chunfeng李淳風(602-670 C.E.), the main editor of a 7th century edition of Ten Canons of Mathematics, was a contemporary of Jia Gongyan’s who also wrote commentaries on mathematical canons. By comparing the two souces, we shall see that they bear witness to different uses of measuring units in computation. Finally, I shall account for the differences between the two types of cultures of computation in social terms, by discussing Jia Gongyan’s and Li Chunfeng’s biographies. In my view, the key fact was that Jia Gongyan was a Confucian scholar while Li Chunfeng more or less was not.