Funan traded primarily with India and China. However, merchants from the Middle-East likely also traded there. Products from as far way as Rome and Greece also made their way to Funan. A roman coin was actually found in an archeological dig in Oc-Eo.

Many different types of goods were traded in Funan, including tin from the Malaysian Peninsual, Frankincense and Myrrh from the Middle East, camphor from Sumatra, Sandalwood from Timor, Spices, Silk from China, and Roman glassware. Funan also traded their local products to foreigners, including tortoise shell and feathers from exotic birds.

On their way to Funan, Indian merchants merchants docked their ships, unloaded their cargo (the goods they were selling) and crossed a small section of land located in Tun-Sun. Once they reached the sea on the other side, they loaded the cargo back onto ships and continued the journey to their destination. This small piece of land was called the Isthmus of Kra. The reason merchants decided to cross the Isthmus of Kra was because sailing techniques were not advanced enough to travel the long distance down the Malaysian peninsula. Also, sailing technology was not quite good enough to make this long journey by sea. Therefore, it made sense to cross the land, as it was less dangerous than travelling the whole distance by sea.