The Karakoram is bounded on the east by the Aksai Chin plateau, on the northeast by the edge of the Tibetan Plateau and on the north by the river valleys of the Yarkand and Karakash rivers beyond which lie the Kunlun Mountains. At the northwest corner are the Pamir Mountains. The southern boundary of the Karakoram is formed, west to east, by the Gilgit, Indus and Shyok rivers, which separate the range from the northwestern end of the Himalaya range proper. These rivers flow northwest before making an abrupt turn southwestward towards the plains of Pakistan. Roughly in the middle of the Karakoram range is the Karakoram Pass, which was part of a historic trade route between Ladakh and Yarkand but now inactive.