The entry point of the river at the Indo–Nepal border is also the confluence called Triveni with rivers Pachnad and Sonha descending from Nepal. Pandai river flows into Bihar (India) from Nepal in the eastern end of the Valmiki Sanctuary and meets Masan. The Gandak flows southeast 300 kilometres (190 mi) across the Gangetic plain of Bihar state through West Champaran, Gopalganj, Saran and Muzaffarpur districts.