The Kingdom was visited regularly by trading ships from China, India, Persia, Japan, the Ryukyu Islands and from as far away as Europe, International trade was a major source of Ayutthaya's wealth and strength. People used both money and barter systems. The Foreign Affairs department was founded to control the trade with foreigners. Its role was to identify those products that foreigners would be frobidden to buy from the People of Ayutthaya. In addition, it decied which froeign products could be imported by the governments before selling to the people.
Ayutthaya's main income was from the export of agricultural products such as rice, betel palms, pepper, sappanwood etc. The main imports were raw silk, clothing, pottery etc. In addition the government had other sources of income such as the garden tax, gambling tax, tribute, fines and port dues etc.