Alfred Russel Wallace lived for 8 months at
Simunjan District with a mining engineer, Robert Coulson, who had explored what is now northern
Sarawak for mineral ores. Coulson later wrote to Wallace about finding bones in a number of caves in Sarawak. On further enquiry, Wallace learned that one cave in question "was situated in the district between Sarawak and Bruni (
Brunei), on a mountain some distance inland." In March 1864, Wallace favoured Coulson to explore the caves. However, later in May 1864, G. J. Ricketts, a British Consul to Sarawak was appointed to undertake the work. Ricketts did not remain in the post for long and subsequently
Alfred Hart Everett was chosen to undertake the work. Everett surveyed 32 caves in three areas, including Niah/Subis (near
Miri) and "Upper Sarawak Proper". However, the first published account of a visit to the 'The Caves of Mount Sobis', long attributed to Everett, is now known to have been by
William Maunder Crocker. In the 1950s,
Tom Harrisson, the curator of
Sarawak State Museum was searching for evidence of ancient human activity in Sarawak. He came across Niah Cave, which showed no evidence of ancient human activity in the area. However, he inferred that since the cave was cool and dry and there were millions of bats and swiflets which could be used as food, ancient humans could have lived in the cave. Therefore, in October 1954, Harrisson with his two friends, Michael Tweedie and Hugh Gibb spent two weeks examining the Niah. They found evidence of long term human occupation, habitation, and burial. In 1957, the Sarawak museum organised a larger expedition with transport and equipment from Brunei Shell Petroleum and Sarawak Oilfields Ltd (Shell). Earthernware, shell scrapers, shell ornaments, stone pounders, bone tools, and food remains were found. in February 1958. Tom Harrisson also discovered Neolithic burial sites from 2,500 to 5,000 years ago. The discoveries led to more expeditions in 1959, 1965, and 1972. In 1960, Don Brothwell concluded that the Deep Skull belonged to an adolescent male who may be closely related to an indigenous Australian from
Tasmania. There is a lack of
paleogeography,
stratigraphy, and archeological relationships to support Tom Harrisson's work. Another dating of the charcoal and the Deep Skull itself was done in 2000. In 2010 and 2021, the Sarawak state government nominated the park for a
UNESCO's
World Heritage Site title. In 2020, all 122 pieces of Niah human remains were returned to Sarawak. Niah National Park was included in the UNESCO's World Heritage Site list on 27 July 2024. ==Geography==