Vassal states are willing to join the Qing Dynasty's tributary system, primarily driven by interests: similar to contemporary international politics, their demands include: First, obtaining political endorsement from the Qing Dynasty to enhance the legitimacy of their regime within the region; Second, leveraging the tributary relationship to conduct tribute trade, receiving rewards far exceeding the value of the tribute items, and maintaining stable civilian trade channels; Third, seeking military protection from the Qing Dynasty when facing external threats.