Brunei i / b run a/ , officially the State of Brunei, the Abode of Peace [14] ( Malay: Negara Brunei Darussalam, Jawi : , Arabic: ), is a sovereign state located on the north coast of the island of Borneo, in Southeast Asia. Apart from its coastline with the South China Sea , it is completely surrounded by the state of Sarawak , Malaysia, and it is separated into two parts by the Sarawak district of Limbang. It is the only sovereign state completely on the island of BORNEO, with the remainder of the island forming parts of Malaysia and Indonesia . Brunei's population was 401,890 in July 2011. ] The official national history claims that Brunei can trace its beginnings to the 7th century, when it was a subject state named P'o-li, in the Sumatra- centric Srivijayan empire. It later became a vassal state of the Java-centric Majapahit empire. Brunei became a sultanate in the 14th century, under a newly converted Islamic sultan Muhammad Shah . At the peak of Bruneian Empire , Sultan Bolkiah (reigned 14851528) had control over the northern regions of Borneo, including modern-day Sarawak and Sabah, as well as the Sulu archipelago off the northeast tip of Borneo, Seludong (modern day Manila), and the islands off the northwest tip of Borneo. The thalassocracy was visited by Spain's Magellan Expedition in 1521 and fought Spain in 1578's Castille War . The Bruneian Empire began to decline, reaching its modern shape in 1890 after the progressive 19th century ceding of Sarawak to the Kingdom of Sarawak and the ceding of Sabah to the British North Borneo Chartered Company . Brunei became a British protectorate in 1888 and was assigned a British Resident in 1906. In the years after the Japanese wartime occupation during World War II , it formalised a constitution and fought an armed rebellion . Brunei regained its independence from the United Kingdom on 1 January 1984. Economic growth during the 1970s and 1990s, averaging 56% from 1999 to 2008, has transformed Brunei into a newly industrialised country. Brunei has the second highest Human Development Index among the South East Asia nations after Singapore, and is classified as a developed country. According to the International Monetary Fund (IMF), Brunei is ranked fifth in the world by gross domestic product per capita at purchasing power parity. The IMF also states in a 2011 estimate that Brunei was one of two countries (the other being Libya) with their public debt at 0% of the national GDP. Forbes also ranks Brunei as the fifth richest nation out of 182 nations due to its extensive petroleum and natural gas fields.[