the examination bureau (門下省, Menxia Sheng), the legislative bureau (內史省, Neishi Sheng), the Palace Library – while abolishing the eunuch bureau and replacing it with the palace bureau (殿內省, Diannei Sheng). He established three additional independent agencies and five independent departments. He also organized the imperial army into 16 corps. He abolished three levels of noble titles—the counts, the viscounts, and the barons—keeping only the princes, the dukes, and the marquesses. Also in summer 607, Emperor Yang embarked on a tour of the northern provinces, building an imperial highway from Chang'an to Jinyang (晉陽, the capital of Bing Province). He then personally visited the imperial tent of Ashina Rangan, whose display of submission and loyalty caused Emperor Yang to bestow much honor and wealth on him. When the senior officials Gao Jiong, Yuwen Bi (), and Heruo Bi privately expressed disapproval, Emperor Yang discovered their criticism and put all of them to death, while removing Su Wei, who also discouraged him from giving excessive rewards to Ashina Rangan, from his post. (Traditional historians attribute Gao's death to Gao's refusal to keep Chen Shubao's Consort Zhang alive in 589.) As Xiao Cong had a deep friendship with Heruo Bi, and there had been rumors that the Xiaos would rise again, the superstitious Emperor Yang also removed Xiao Cong from his post. Qimin visited Yangdi at Yulin. Also in 607, at the instigation of Pei Ju, Emperor Yang reopened relations with Xiyu states. In spring 608, Emperor Yang conscripted over a million men to construct the Yongji Canal (), from the Yellow River to Zhuo Commandery (涿郡, roughly modern Beijing). It was said that there were not enough men, and he started conscripting women as well. In 608, after persuasion by the Sui official Cui Junsu (), the Western Tujue khan (Ashina Rangan's western rival), the Heshana Khan Ashina Daman, whose mother was Han, submitted to Sui as a vassal. However, also in 608, Emperor Yang received a letter claiming to be from the Emperor of Japan, Duolisibigu (多利思比孤, now commonly believed to be Prince Shōtoku), stating, "The Son of Heaven where the sun rises, to the Son of Heaven where the sun sets, may good health be with you." Displeased by what he saw as insolence, he ordered that in the future, "insolent" letters from other states not be submitted to him. Also in 608, initially over disputes over women (Yang