The most powerful state in Asia at the time was China. Funan wanted to have a good relationship with this superpower, so they sent gifts to the Chinese Emperor, which were called tributes. In return, the Chinese Emperor recognized Funan as a vessel state. This means that China regarded Funan as a friendly by inferior state. As a vessel state of China, Funan could rely on China for favorable trade relations and protection. Additionally, in times of conflict (fighting or disputes) in Southeast Asia, Funan could rely on China for support.

Funan also had their own vassal states. One of those was Tun-Sun, which is located near the modern day Chumphon and Ranong. This state was conquered by a powerful king of Funan named Fan Shi-Man. Controlling the Tun-Sun was very important for Funan, as it was the primary route from Oc-Eo to to India, and therefore important for trade.