太武帝
What appeared evidence late in Feng Ba's reign, but even more so in Feng Hong's reign, were incessant attacks by the neighboring rival Northern Wei. This appeared to be particularly true after Northern Wei annexed all of the territory of Xia in 431 and therefore no longer had a major western rival to deal with. Emperor Taiwu of Northern Wei made periodic attacks to pillage Northern Yan territory and then withdraw, draining Northern Yan of food supplies and other resources and weakening it.