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.

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.

Ricketts did not remain in the post for long and subsequently Alfred Hart Everett was chosen to undertake the work.

Therefore, in October 1954, Harrisson with his two friends, Michael Tweedie and Hugh Gibb spent two weeks examining the Niah.

[4] The expedition team led by Barbara Harrisson discovered the "Deep Skull" in the "Hell Trench" (named for its unusually hot condition) at 101 to 110 inches below surface[5] in February 1958.

[8] 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.

[11] In 2016, further research done by Darren Curnoe noted that the Deep Skull was more resembling of a female adolescent and is more closely resembling the indigenous people of Borneo rather than Tasmanians or the two layer hypothesis which stated that original population of Southeast Asia were emigrated from Australia and later integrated with people from China.

[5][11] In 2010 and 2021, the Sarawak state government nominated the park for a UNESCO's World Heritage Site title.

More recent studies published in 2006 have shown evidence of the first human activity at the Niah caves from ca.

[19] Items found at the Niah Cave include Pleistocene chopping tools and flakes, Neolithic axes, adzes, pottery, shell jewellery, boats, mats, then iron tools, ceramics and glass beads dating to the Iron Age.

Every section of the ceiling in the caves where there are swiftlets roosting is privately owned and only the owner has the right to collect the nests.

The collector climbs up hundreds of feet on a single pole to the cave ceiling and scrapes off the nest in flickering candlelight.