The kingdom of the Magadha, before its expansion, corresponded to the modern districts of Patna, Jehanabad, Nalanda, Aurangabad, Arwal, Nawada and Gaya in southern Bihar. It was bounded on the north by the river Ganges, on the east by the river Champa, on the south by the Chota Nagpur Plateau, and on the west by the Son River.