Yong-le: Year 4, Month Intercalary 7, Day 2
15 Aug 1406
Imperial orders were sent to the Cheng-guo Duke Zhu Neng, regional commander of the force being sent on expedition to punish Annam. The orders read: "When the army enters Annam and takes prefectural cities, none of the registers, maps or gazetteers which are obtained are to be destroyed."
Zhong-yang Yan-jiu yuan Ming Shi-lu, volume 11, page 835