If you are looking for tropical wet evergreen forests you must visit Dehing Patkai Wildlife Sanctuary. Spread across an area of 111.19 sq km this sanctuary is unfolded between Dibrugarh and Tinsukia districts of Assam Valley.
It is also close to the border of Arunachal Pradesh and also has World War II cemeteries along with the famous Stillwell Road. You will find mammals such as Chinese Pangolin, Stump-Tailed Macaque, Himalayan Black and Malayan Giant Squirrels to name a few.
There are also many species of birds found here including Lesser Adjutant Stork, White Winged Wood Duck, White Cheeked Hill Partridge, Khaleej Pheasant, Grey Peacock-Pheasant, Rufus Necked Hornbill among others.
The best time to visit this sanctuary would be between the months of September and March. This sanctuary is located 80 km from the Mohanbari (Dibrugarh) Airport and also close to the towns of Digboi, Duliajan and Margherita in Upper Assam.