The tomb of a ruler of Po-ni in Nanjing , Jiangsu , China. One of the earliest Chinese records is the AD letter to Chinese emperor from the ruler of Po-ni, which some scholars believe to refer to Borneo.
In , the Sulus attacked Po-ni, looting it of treasure and gold. A fleet from Majapahit succeeded in driving away the Sulus, but Po-ni was left weaker after the attack. European influence gradually brought an end to the regional power , as Brunei entered a period of decline compounded by internal strife over royal succession. Since the Spanish regarded Brunei the center of Islamic preaching in the Philippines  Spain declared war in , planning to attack and capture Kota Batu , Brunei's capital at the time.
The former had travelled to Manila , then the centre of the Spanish colony, Manila itself was captured from Brunei and Christianised, Pengiran Seri Lela came to offer Brunei as a tributary to Spain for help to recover the throne usurped by his brother, Saiful Rijal. The expedition consisted of Spanish, 1, Filipino natives and Borneans.
In Jerudong, they made plans to chase the conquering army away from Brunei. Suffering high fatalities due to a cholera or dysentery outbreak,   the Spanish decided to abandon Brunei and returned to Manila on 26 June , after 72 days. Before doing so, they burned the mosque, a high structure with a five-tier roof. There was suspicion he could have been poisoned by the ruling sultan. What was called the Castilian War was seen as a heroic episode, with the Spaniards being driven out by Bendahara Sakam, purportedly a brother of the ruling sultan, and a thousand native warriors.
Most historians consider this to be a folk-hero account, which probably developed decades or centuries after. British adventurer James Brooke negotiating with the Sultan of Brunei , which led to the signing of the Treaty of Labuan , British intervention See also: British Brunei Administrators Boundaries of Brunei green since The British have intervened in the affairs of Brunei on several occasions.
Britain attacked Brunei in July due to internal conflicts over who was the rightful Sultan. The sultan granted land now Sarawak to James Brooke , who had helped him quell a rebellion and allowed him to establish the Kingdom of Sarawak. Over time, Brooke and his nephews who succeeded him leased or annexed more land.
Brunei lost much of its territory to him and his dynasty, known as the White Rajahs. The treaty said that the sultan "could not cede or lease any territory to foreign powers without British consent"; it provided Britain effective control over Brunei's external affairs, making it a British protectorate which continued until They did not regard either Brunei or the Kingdom of Sarawak as 'foreign' per the Treaty of Protection.
This final annexation by Sarawak left Brunei with its current small land mass and separation into two parts. Over time, the resident assumed more executive control than the sultan. The residential system ended in Cochrane, smelled oil near the Seria river in late In , gas seepages were reported in the area.
Seria Well Number 2 was drilled on 19 August , and, as of [update] , continues to produce oil. In , oil production was at more than six million barrels. Japanese occupation This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. December Main article: Japanese occupation of British Borneo Ahmad Tajuddin , the 27th Sultan of Brunei , with members of his court in April , eight months before the Japanese invaded Brunei.
After six days fighting, they occupied the entire country. The Japanese had proposed that Pengilly retain his position under their administration, but he declined. While the British officials were under Japanese guard, Ibrahim made a point of personally shaking each one by the hand and wishing him well.
During the later part of the occupation, he resided at Tantuya, Limbang and had little to do with the Japanese. Most of the Malay government officers were retained by the Japanese. Brunei's administration was reorganised into five prefectures, which included British North Borneo. Ibrahim hid numerous significant government documents from the Japanese during the occupation.
Although in the area the day of the atomic bombing of Hiroshima , Yusuf survived. Japanese battleships at Brunei in October The British had anticipated a Japanese attack, but lacked the resources to defend the area because of their engagement in the war in Europe.
The troops from the Punjab Regiment filled in the Seria oilfield oilwells with concrete in September to deny the Japanese their use. The remaining equipment and installations were destroyed when the Japanese invaded Malaya. By the end of the war, 16 wells at Miri and Seria had been restarted, with production reaching about half the pre-war level. Coal production at Muara was also recommenced, but with little success. During the occupation, the Japanese had their language taught in schools, and Government officers were required to learn Japanese.
The local currency was replaced by what was to become known as duit pisang banana money. From hyper-inflation destroyed the currency's value and, at the end of the war, this currency was worthless. Allied attacks on shipping eventually caused trade to cease.
Food and medicine fell into short supply, and the population suffered famine and disease. The airport runway was constructed by the Japanese during the occupation, and in Japanese naval units were based in Brunei Bay and Labuan. The naval base was destroyed by Allied bombing, but the airport runway survived. The facility was developed as a public airport.
In the Allies began a bombing campaign against the occupying Japanese, which destroyed much of the town and Kuala Belait, but missed Kampong Ayer. They were supported by American air and naval units.
Brunei town was bombed extensively and recaptured after three days of heavy fighting. Many buildings were destroyed, including the Mosque.
It consisted mainly of Australian officers and servicemen. The Brunei State Council was also revived that year. They also had to put out the fires on the wells of Seria, which had been set by the Japanese prior to their defeat. The party intended to "preserve the sovereignty of the Sultan and the country, and to defend the rights of the Malays ".
The party was dissolved in due to inactivity. In , a new constitution was written declaring Brunei a self-governing state, while its foreign affairs, security, and defence remained the responsibility of the United Kingdom. The rebellion partially affected Brunei's decision to opt out of the Malaysian Federation.
In May , the Sultan, Resident and High Commissioner met to discuss the findings of the committee. They agreed to authorise the drafting of a constitution. The British Government later accepted the draft constitution. It included the following provisions: Brunei was responsible for its internal administration. The British Government was responsible for foreign and defence affairs only.
The post of Resident was abolished and replaced by a British High Commissioner. Five councils were set up: