Before 1928, Manas National Park was a reserve forest and called Manas R.F. and North Kamrup R.F. The park’s 360 sq. km area was designated as a wildlife sanctuary on 1st October, 1928. Between 1951 and 1955, the forest area was increased to 391 km² and Manas Biosphere Reserve was established in the year 1973. In 1985, the park was declared as the Natural World Heritage Site by UNESCO.Later in the year 1990, Kahitama R.F. and the Panbari R.F. were also included to create Manas National Park. But in 1992, UNESCO confirmed the park as 'World Heritage Site in Danger' because of poaching and terrorist activities. In 2008, the area of the national park was increased to 950 km². In 2011, Manas National Park was removed from UNESCO's list of 'World Heritage Site in Danger' due to its effective conservation efforts.