After passing Pi (Pe) in Tibet, the river turns suddenly to the north and northeast and cuts a course through a succession of great narrow gorges between the mountainous massifs of Gyala Peri and Namcha Barwa in a series of rapids and cascades. Thereafter, the river turns south and southwest and flows through a deep gorge (the "Yarlung Tsangpo Grand Canyon") across the eastern extremity of the Himalayas with canyon walls that extend upward for and more on each side. During that stretch, the river enters northern Arunachal Pradesh state in northeastern India, where it is known as the Dihang (or Siang) River, and turns more southerly.