The Sutlej is sometimes known as the Red River. It isthe easternmost tributary of the Indus River. Its sourceis Lake Rakshastal in Tibet. From there, it flows at firstwest-northwest for about 260 kilometres (160 mi) to theShipki La pass, entering India in Himachal Pradesh state.It then turns slightly, heading west-southwest for about360 kilometres (220 mi) to meet the Beas River nearMakhu, Firozpur district, Punjab state.