The Ariyagama sacred area located on the banks of the Deduru Oya in Mugunuwatawana in Chilaw is also known as Nariyagama Veherakele. The change in the course of Deduru Oya River due to meandering throughout the ages had destroyed the remnants of the monastic complex. A portion of the Dagoba, which was located near the bank of the river had been submerged. The large quantity of potsherds found in the premises are the remnants of large flagons. It could be surmised that a warehouse complex belonging to the Salatitha, the port of the Deduruoya estuary may have existed here. This monastery may have been a sacred area associated with the warehouse complex. The discovery of Roman coins from archaeological excavations conducted in the monastic complex suggests that the place bears testimony to a sacred area connected to a town where trade has flourished.