This was a formal canonization, which set the master-subordinate relationship.
Previously, the Chinese Han submission was only in words and notional.
This can be seen from Qiao Kangquan still claiming himself as the king of Hanzhong.
It was absurd for vassals and sovereigns both to be kings, with no distinction of superiority and inferiority.
Now, taking advantage of the opportunity of relocation, the master-subordinate relationship is formally established, and the leading position of Chu State in Jianchuan State has been established, making it the third vassal state under the Chu State tribute system, which is quite necessary.
Qiao Kangquan also understood this point, so he had no dissatisfaction or regrets about his rank being reduced by one level, changing from a king to a duke.
It's just a matter of title.
If lowering his title by one level could exchange for the territories of three prefectures, then he would rather have his title reduced even more.
