The ancient Mataram Kingdom in Central Java is one of the Hindhu–Buddhist kingdoms that had several written inscriptions. Most inscriptions about the management of water transportation were issued by King Balitung (9th century), King Sindhok (10th century) and King Airlangga (11th century). These inscriptions contained information about the development of patterns of trade conducted through river ways, mainly Solo and Berantas Rivers, as the main trade lanes. Archaeological and geographical evidences found in the areas surrounding the aforementioned two major rivers indicate attempts made to improve the economy by trading via waterways that had been explored at that time. Evidences found around the two rivers indicate existence of small port areas in the ancient Mataram era. In addition, on the basis of the toponymy of the areas around the harbours, this study reveals the functions of the ports. The findings of this study reveal the methods of using tracks and patterns of waterway transportation in trading at that time.