Core territory of present-day North Borneo was established as the Kingdom of Sarawak by Sir James Brooke in 1841. Brooke received the territory of Sarawak from the Sultanate of Brunei as a reward for helping fight piracy and insurgency and founded the English-descended Brooke dynasty, commonly called the "White Rajahs", to rule over the territory. As the first White Rajah, he retained many of the customs and symbols of Malay monarchy and combined them with his own style of absolute rule.
The Brookes established the policy of paternalism in order to protect the indigenous population against exploitation by the Western business interests. They governed with the aid of the Muslim Malays and enlisted the Ibans and other "Dayaks" as a contingent militia. The White Rajahs also encouraged the immigration of Chinese merchants but forbade the Chinese to settle outside of towns in order to minimize the impact on the Dayak way of life.
As the effect of Anglo-Japanese Treaty of 1940, Japanese troops entered Sarawak and occupied the northern part of the island of Borneo in 1940. Sarawak was placed under provisional Japanese protection as the British forces concentrated their defense on Malay peninsula against the advanced Thai forces that already occupied northern Malaya. Japan occupying Miri on September 7 and Kuching on September 14, 1940 and holding both territories for the duration of World War II until the area was returned back under the British controls.