Brunei Darussalam is one Asia's oldest kingdoms, having been in existence for more than 1,500 years, trading with the Asian mainland as early as AD 518 and emerging as an imperial power from the fifteenth to the sixteenth centuries. Chinese and Arabic annals record a forerunner to the present Brunei Sultanate, which the Chinese called Po-ni, trading with China during the 6th, 7th and 8th centuries A.D. This early kingdom was apparently conquered by the Sumatran Hindu Empire in the early ninth century and had allegiance to the Javanese Majapahit kingdom from the13th to 15th century. In the early 15th century, with the decline of the Majapahit kingdom and widespread conversion to Islam, Brunei became an independent sultanate.

The Sultanate of Brunei's influence peaked between the 15th and 17th centuries when its control extended over coastal areas of northwest Borneo, parts of Kalimantan and the southern Philippines. Brunei subsequently entered a period of decline brought on by internal strife over royal succession, colonial expansion of European powers and piracy. The Dutch, Portuguese and Spanish began arriving after the 16th century. Brunei lost outlying possessions to the Spanish and the Dutch, its power gradually declining as the British and Dutch colonial empires expanded. Sarawak was lost by 1841. Meanwhile, the British North Borneo Company was expanding its control over territory in northeast Borneo. By 1888, Brunei had become a British protectorate and, by 1905, a British dependency. It was occupied by Japan during World War II, being liberated by Australia in 1945.

By 1959, the sultan had regained control over internal affairs, achieving the promulgation on 29th September 1959 of a written Constitution, which gave the State self-government, made the Sultan supreme executive authority in the country, and changed the post of British Resident to High Commissioner, who continued to advise the Sultan on all matters other than those relating to Islam and Malay customs. The British government only retained responsibility for matters of defence and external affairs. To assist the Sultan, the Privy Council, Council of Ministers and State Legislative Council were formed.

In 1963, Brunei was the only Malay state to choose to remain a British dependency rather than join the Malaysian Federation. The sultanate passed from father to son in 1967. On January 4, 1979, Brunei and the United Kingdom signed a new treaty of friendship and cooperation. On January 1, 1984, Brunei Darussalam became a fully independent state. Soon after, in quick succession, Brunei Darussalam became a member of ASEAN (Association of Southeast Asian Nations), OIC (Organisation of Islamic Conference), the Commonwealth and the United Nations.