In the last few years of Emperor Daowu's reign, he became increasingly harsher in his treatment of his officials. For example, in 406, as he planned the expansion of Pingcheng with intent to make it into an impressive capital, he initially had his official Mo Ti (), an accomplished civil engineer, plan the city's layout, but over a relatively minor issue where Mo was not very careful, ordered Mo to commit suicide—and then used Mo's layout anyway. He also made increasing visits to Chaishan Palace (豺山宮, in modern Shuozhou, Shanxi), often spending months there at a stretch. Other key officials that he killed during this period included his cousin Tuoba Zun the Prince of Changshan, Yu Yue, Monalou Ti (), and Tuoba Yi the Prince of Wei.