Tirthan River, a tributary of the Beas River
, originates from the base of an offshoot of the main Himalayan
range, to the south-east of Kullu, in Himachal Pradesh
The river flows in the south-west direction and merges with the Beas River at Larji just before it cuts across the Dhauladhar Range. Lower down, the valley opens up and it is fairly wide near its confluence with the Beas River.