 The river, Sariswa (Sirsiya), a tributary of the Burhi Gandak, originates from Pathlahia hill of the dense Ramban forests in Nepal, its course roaming through the subdivision cutting through Bara and Parsa districts in Nepal and Raxaul in Bihar, India.It flows southwards from the place of its origin for about 15 km in Nepal and then enters India at Raxaul.From here, the river flows about 20 km in India and joins Burhi Gandak near Sugauli in East Champaran district.