The Manas National Park was declared a sanctuary on October 1, 1928 with an area of 360 km². Manas bioreserve was created in 1973. Prior to the declaration of the sanctuary it was a Reserved Forest called Manas R.F. and North Kamrup R.F. It was used by the Cooch Behar royal family and Raja of Gauripur as a hunting reserve.
In 1951 and 1955 the area was increased to 391 km². It was declared a World Heritage site in December 1985 by UNESCO. Kahitama R.F. the Kokilabari R.F. and the Panbari R.F. were added in the year 1990 to form the Manas National Park. In 1992, UNESCO declared it as a world heritage site in danger due to heavy poaching and terrorist activities. In 25 February 2008 the area was increased to 950 km². On 21st June 2011, it was removed from the List of World Heritage in Danger and was commended for its efforts in preservation.