Borneo (/ˈbɔːrnioʊ/; also known as Kalimantan in the Indonesian language) is the third-largest island in the world, with an area of 748,168 km2 (288,869 sq mi), and population of 23,053,723 (2020 national censuses).

[1][2][3] Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda Islands, located north of Java, west of Sulawesi, and east of Sumatra.

[14] In Indianized Malay era the name Kalamanthana was derived from Sanskrit terms kala (time or season) and manthana (churning, kindling or creating fire by friction),[15] which possibly describes the heat of the weather.

[18] Borneo was formed through Mesozoic accretion of microcontinental fragments, ophiolite terranes and island arc crust onto a Paleozoic continental core.

At the beginning of the Cenozoic Borneo formed a promontory of Sundaland which partly separated from Asian mainland by the proto-South China Sea.

[19] The oceanic part of the proto-South China Sea was subducted during the Paleogene period and a large accretionary complex formed along the northwestern of the island of Borneo.

[19] The uplift may have also resulted from shortening due to the counter-clockwise rotation of Borneo between 20 and 10 mega-annum (Ma) as a consequence of Australia-Southeast Asia collision.

[19] Before sea levels rose at the end of the last ice age, Borneo was part of the mainland of Asia, forming, with Java and Sumatra, the upland regions of a peninsula that extended east from present day Indochina.

Deeper waters separating Borneo from neighbouring Sulawesi prevented a land connection to that island, creating the divide known as Wallace's Line between Asian and Australia-New Guinea biological regions.

[33] It is the centre of the evolution and distribution of many endemic species of plants and animals, and the rainforest is one of the few remaining natural habitats for the endangered Bornean orangutan.

In November 2018, scientists reported the discovery of the oldest known figurative art painting, over 40,000 (perhaps as old as 52,000) years old, of an unknown animal, in the cave of Lubang Jeriji Saléh on the island of Borneo.

[citation needed] According to ancient Chinese (977),[54]: 129  Indian and Japanese manuscripts, western coastal cities of Borneo had become trading ports by the first millennium AD.

[55] In Chinese manuscripts, gold, camphor, tortoise shells, hornbill ivory, rhinoceros horn, crane crest, beeswax, lakawood (a scented heartwood and root wood of a thick liana, Dalbergia parviflora), dragon's blood, rattan, edible bird's nests and various spices were described as among the most valuable items from Borneo.

Archaeological findings in the Sarawak river delta reveal that the area was a thriving centre of trade between India and China from the 6th century until about 1300.

[56] Stone pillars bearing inscriptions in the Pallava script, found in Kutai along the Mahakam River in East Kalimantan and dating to around the second half of the 4th century, constitute some of the oldest evidence of Hindu influence in Southeast Asia.

The religion of Islam entered the island in the 10th century,[62] following the arrival of Muslim traders who later converted many indigenous peoples in the coastal areas.

Although they managed to defeat the sultanate the next year and declared a blockade on all ports in Borneo except Brunei, Banjarmasin and Pontianak, the project was cancelled by the British governor-general Lord Minto in India as it was too expensive.

[81] The Dutch began to intervene in the southern part of the island upon resuming contact in 1815, posting residents to Banjarmasin, Pontianak and Sambas and assistant-residents to Landak and Mampawa.

[82][83] The Sultanate of Brunei in 1842 granted large parts of land in Sarawak to the British adventurer James Brooke, as a reward for his help in quelling a local rebellion.

[89] Before the acquisition by the British, the Americans also managed to establish their temporary presence in northwestern Borneo after acquiring a parcel of land from the Sultanate of Brunei.

[97][98] During this time, the British sponsored a large number of Chinese workers to migrate to northern Borneo to work in European plantation and mines,[99] and the Dutch followed suit to increase their economic production.

[101] The British and Dutch governments had signed the Anglo-Dutch Treaty of 1824 to exchange trading ports in Malay Peninsula and Sumatra that were under their controls and assert spheres of influence.

This resulted in indirectly establishing British- and Dutch-controlled areas in the north (Malay Peninsula) and south (Sumatra and Riau Islands) respectively.

[108] Following the formation of resistance movements in northern Borneo such as the Jesselton Revolt, many innocent indigenous and Chinese people were executed by the Japanese for their alleged involvement.

[114] In addition, of the total of 17,488 Javanese labourers brought in by the Japanese during the occupation, only 1,500 survived mainly due to starvation, harsh working conditions and maltreatment.

In May 1945, officials in Tokyo suggested that whether northern Borneo should be included in the proposed new country of Indonesia should be separately determined based on the desires of its indigenous people and following the disposition of Malaya.

[121] While nationalist guerrillas supporting the inclusion of southern Borneo in the new Indonesian republic were active in Ketapang, and to lesser extent in Sambas where they rallied with the red-white flag which became the flag of Indonesia, most of the Chinese residents in southern Borneo expected to be liberated by Chinese Nationalist troops from mainland China and to integrate their districts as an overseas province of China.

[126][127] Sukarno, as the president of the new republic, perceiving the British trying to maintain their presence in northern Borneo and the Malay Peninsula, decided to launch a military infiltration, later known as the confrontation, from 1962 to 1969.

[136] With the continuous opposition from Indonesia and the Philippines, the Cobbold Commission was established to discover the feeling of the native populations in northern Borneo; it found the people greatly in favour of federation, with various stipulations.

[141][142] In August 2019, Indonesian president Joko Widodo announced a plan to move the capital of Indonesia from Jakarta to a newly established location in the East Kalimantan province in Borneo.