The eastern extremity of Upper Wakhan is known as the "Pamir Knot", the area where the Himalayas, Tian Shan, Karakoram, Kunlun, and Hindu Kush ranges meet. West of the Pamir Knot is the Little Pamir, a broad U-shaped grassy valley 100 km long and 10 km wide, which contains Chaqmaqtin Lake, the headwaters of the Aksu or Murghab River. At the eastern end of the Little Pamir is the Tegermansu Valley, from where the closed Tegermansu Pass (4,827 m) leads to China. The Great Pamir or "Big Pamir", a 60 km long valley south of Zorkol lake, drained by the Pamir River, lies to the northwest of the Little Pamir.