As we have already seen, there is no reasonable ground to suppose that Tsʽao Kung tampered with the text. But the text itself is often so obscure, and the number of editions which appeared from that time onward so great, especially during the Tʽang and Sung dynasties, that it would be surprising if numerous corruptions had not managed to creep in. Towards the middle of the Sung period, by which time all the chief commentaries on Sun Tzǔ were in existence, a certain 吉天保 Chi Tʽien-pao published a work in 15 chüan entitled 十家孫子會注 Sun Tzǔ with the collected commentaries of ten writers