Yong-le: Year 12, Month 6, Day 8
24 Jun 1414
On this day, the following were established in Jiao-zhi: 1. The Yi-an, Xin-ping and Shun-hua Guards. 2. The Yan-zhou Independent Battalion. 3. The Nan-jing Independent Battalion under the Yi-an Guard. At this time, the Ying-guo Duke Zhang Fu felt that, because the four prefectures bordered on Laos, Champa and the Siamese man and because their area was broad and the yi population great, there needed to be administrative control imposed. He deliberated with the Qian-guo Duke Mu Sheng and then requested approval to establish a guard in each of the prefectures, that native troops be registered and that native-official guard commanders and battalion commanders handle the affairs of the guards and battalions. He also requested that seals be supplied. The Heir Apparent approved all the requests.
Zhong-yang Yan-jiu yuan Ming Shi-lu, volume 13, page 1766