The Brahmaputra, Irrawady and Mekong rivers originate in Tibet and flow through narrow and parallel mountain ranges in their upper reaches. Of these rivers, Brahmaputra makes a “U” turn in its course to flow into India. This “U” turn is due to

The Brahmaputra river, known as the Yarlung Tsangpo in Tibet, flows eastward parallel to the Himalayas before reaching the Namcha Barwa peak [3]. At this point, the river makes a dramatic 'U' turn, also known as the 'Great Bend', to enter India through the Dihang gorge in Arunachal Pradesh [4]. This sharp hairpin bend is geologically attributed to the syntaxial bending of the young Himalayan ranges [1]. The Himalayas terminate suddenly at their eastern and western extremities, where the mountain ranges and tectonic strikes undergo deep knee-bend flexures southward [1]. These syntaxial bends occur because the geologically young and flexible mountain series were bent around pivotal points during their tectonic upheaval [4]. While the Himalayas are indeed a result of tertiary folding and uplift, the specific 'U' turn of the river is a direct consequence of this syntaxial structural feature [1].

Sources

1. [2] CONTEMPORARY INDIA-I ,Geography, Class IX . NCERT(Revised ed 2025) > Chapter 3: Drainage > The Brahmaputra River System > p. 20
2. [3] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 3: The Drainage System of India > 3. The Brahmaputra River > p. 17
3. [4] INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.) > Chapter 2: Structure and Physiography > THE HIMALAYAS AND OTHER PENINSULAR MOUNTAINS > p. 9
4. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 2: Physiography > The Syntaxial Bends of the Himalaya > p. 17