The Ahom kingdom was based on the Paik system, a type of corvee labor that is neither feudal nor Asiatic. The Ahoms introduced wet rice cultivation in upper Assam that was largely a marshy and thinly populated land. With a superior technology of rice cultivation, as well as reclamation of land using dykes, embankments and irrigation systems, the Ahoms established the initial state structures. The first coins were introduced by Suklenmungin the 16th century, though the system of personal service under the Paik system persisted. In the 17th century when the Ahom kingdom expanded to include erstwhile Koch and Mughal areas, it came into contact with their revenue systems and adapted accordingly.