Lohit River

The Lohit River, also known as the Zayul Chu by the Tibetans, is a river in Tibet and India, which joins the Brahmaputra River in the state of Assam. It is formed in the Zayul County of the Tibet Autonomous Region, through a merger of two rivers: the Kangri Karpo Chu (also called Rongto Chu and Zayul Ngu Chu), which originates in the Kangri Karpo range, and Zayul Chu (Chinese: 察隅河; pinyin: Cháyú Hé), which originates to its northeast. The two rivers merge below the town of Rima. The combined river descends through this mountainous region and surges through Arunachal Pradesh in India for 200 kilometres (120 mi) before entering the plains of Assam where it is known as the Lohit River. Tempestuous and turbulent, and known as the river of blood partly attributable to the lateritic soil, it flows through the Mishmi Hills, to meet the Siang (Brahmaputra) at the head of the Brahmaputra valley.

The Lohit-Brahmaputra system is called Dilao by the Bodo-Kachari groups, Tilao by the Ahoms and Tellu by the Mishmis. The Lohit valley lay within the principal territorial zone of the Chutia kingdom, until it was annexed by the Ahoms following the Chutia-Ahom conflicts. D. Nath describes the Chutia territory as being concentrated principally in the river valleys of the Lohit, Subansiri, Brahmaputra and Dihing, with comparatively limited extension into the surrounding hills.