The river is joined by the Ghudara river just below Sarez Lake. From the junction the river is known as the Bartang. The Bartang traces a route down the western Pamir Mountains, flowing before becoming a tributary to the Panj at the border of Tajikistan and Afghanistan. Much of the river lies within the boundaries of Tajik National Park. The Bartang is fed mostly by glacier and snow melt. It is the only river to cross Gorno-Badakhshan from east to west.