The Chitral River properly begins six kilometers north of the town of Chitral, at the confluence of two primary tributaries. The Mastuj River flows down from the northeast, from the high pass into the upper Gilgit River system. The Lutkho the high pass into the upper Gilgit River system. The Lutkho descends from the northwest, from the passes leading into descends from the northwest, from the passes leading into Afghanistan. Their confluence forms a major river set in a wide, fertile valley, flowing south and west, eventually to cross the border into Afghanistan. Joining the Kabul River at historic Jalalabad, it reemerges nto Pakistan to meet the Indus at Attock Fort. As with the Indus and the Jhelum, flows are measured in thousands of cubic feet per secound.