Here is your short paragraph on the Eastern Hills of India or the Purvanchal!
After crossing the Dihang gorge, the Himalayas take a sudden southward turn and form a series of comparatively low hills running in the shape of a crescent with its convex side pointing towards the west.
These hills are collectively called the Purvanchal because they are located in the eastern part of India.
Extending from Arunachal Pradesh in the north to Mizoram in the south, they form India’s boundary with Myanmar. Differing markedly from the Himalaya in the scale of their relief and in their morphology, these hill ranges none-the-less stem from the same orogeny.
In the north is the Patkai Bum which forms the international boundary between Arunachal Pradesh and Myanmar. It is made up of strong sandstone and rises to elevation varying from 2,000 m to 3,000 in. After running for some distance southwards, it merges into Naga Hills where Saramati (3,826 m) is the highest peak. Patkai Bum and Naga Hills form the watershed between India and Myanmar.
The Kohima hills to the west are made up of sandstone and slate and have a very rough topography. South of Naga Hills are the Manipur hills which are generally less than 2,500 metres in elevation. They form boundary between Manipur and Myanmar.
The Barail range separates Naga Hills from Manipur Hills. Further south the Barail Range swings to south-west and then west into Jaintia, Khasi and Garo hills which are an eastward continuation of the Indian peninsular block and has been separated by the Bengal Basin.
South of the Manipur Hills are the Mizo Hills (previously known as the Lushai hills) which have an elevation of less than 1,500 metres. The highest point is the Blue Mountain (2,157 m) in the south. It is obvious that the elevation of the eastern hills decreases as we move from north to south. Although comparatively low, these hill ranges are rather forbidding because of the rough terrain, dense forests and swift streams.