are perennial with the high rate of fall, thus, having the highest hydro-electric power potential in the country. An important aspect of the Arunachal Himalayas is the numerous ethnic tribal community inhabiting in these areas. Some of the prominent ones from west to east are the Monpa, Abor, Mishmi, Nyishi and the Nagas. Most of these communities practise Jhumming .
It is also known as shifting or slash and burn cultivation. This region is rich in biodiversity which has been preserved by the indigenous Figure . : Eastern Himalayas communities. Due to rugged topography, the inter-valley transportation linkages are nominal.
Hence, most of the interactions are carried through the duar region along the Arunachal-Assam border. The Eastern Hills and Mountains These are part of the Himalayan mountain system having their general alignment from the north to the south direction. They are known by different local names. In the north, they are known as Patkai Bum, Naga hills, the Manipur Figure .
: Mizo Hills Figure . : Loktak Lake hills and in the south as Mizo or Lushai hills. These are low hills, inhabited by numerous tribal groups practising Jhum cultivation. Most of these ranges are separated from each other by numerous small rivers.
The Barak is an important river in Manipur and Mizoram. The physiography of Manipur is unique by the presence of a large lake known as ‘Loktak’ lake at the centre, surrounded by mountains from all sides. Mizoram which is also known as the ‘Molassis basin’ which is made up of soft unconsolidated deposits. Most of the rivers in Nagaland form the tributary of the Brahmaputra.
While two rivers of Mizoram and Manipur are the tributaries of the Barak river, which in turn is the tributary of Meghna; the rivers in the eastern part of Manipur are the tributaries of Chindwin, which in turn is a tributary of the Irrawady of Myanmar. The Northern Plains The northern plains are formed by the alluvial deposits brought by the rivers – the Indus, the Ganga and the Brahmaputra. These plains extend approximately , km from the east to