Mount Serumbu, also known as Mount Peninjau, was home to the earliest settlement of Serumbu Bidayuhs some 300 years ago. While on a working visit to Siniawan and Bau, Sir James Brooke was said to have been captivated by Bidayuh Longhouses at the mountain top facing Siniawan. Between 1848 and 1850 with the help of the villagers there, Brooke built a cottage at Bung Muan located just above the settlement.