Emperor Wu carried out an invasion of the Korean Peninsula and established the Commandery of Canghai, but abandoned it in 126 BC. Some of the military colonies established at that time survived into the 4th century, leaving behind various particularly well-preserved funerary artefacts.
The failure of the Mayi operation prompted Emperor Wu to switch the Han army's doctrine from the traditionally more defensive chariot–infantry warfare to a highly mobile and offensive cavalry-against-cavalry warfare. At the same time, he expanded and trained officers from his royal guards.
