The Indonesia–Malaysia border consists of a 1,881 km (1,169 mi) land border that divides the territory of Indonesia and Malaysia on the island of Borneo. It also includes maritime boundaries along the length of the Straits of Malacca, in the South China Sea and in the Celebes Sea.
The land boundary stretches from Tanjung Datu at the northwestern corner of Borneo through the highlands of the Borneo hinterland to the Gulf of Sebatik and the Celebes Sea in the eastern side of the island. The boundary separates the Indonesian provinces of North Kalimantan, East Kalimantan and West Kalimantan from the Malaysian states of Sabah and Sarawak.
The maritime boundary in the Straits of Malacca generally follows the median line between the baselines of Indonesia and Malaysia, running south from the tripoint with Thailand to the start of the maritime border with Singapore. Only part of this boundary has been delimited through a continental shelf boundary treaty in 1969 and a territorial sea boundary treaty in 1970. The continental shelf boundary between Indonesia and Malaysia in the South China Sea is also drawn along the equidistant line between the baselines of the two countries under the 1969 continental shelf boundary.
The border in the Celebes Sea is disputed between the two countries. Part of the dispute was settled by the judgement of the International Court of Justice in the Ligitan and Sipadan Case in 2002 and is now awaiting delimitation between the two countries. However, the two countries still have overlapping claims over the continental shelf, which Indonesia refers to as Ambalat.
There are numerous sea transport crossings between Indonesia and Malaysia, mostly between Indonesia's Sumatra island and Peninsular Malaysia but also between the Indonesian province of North Kalimantan and Malaysia's Sabah state. There are only three official land transport crossing points, all between West Kalimantan and Sarawak. Both the land and maritime borders are relatively porous; many undocumented workers have crossed from Indonesia to Malaysia.
Land border
The territorial division of Borneo gained scant Dutch attention until the arrival of British soldier James Brooke in Sarawak in 1841, which the Dutch East Indies Government in Batavia (Jakarta) sensed as a threat to their hegemonic position over Bornean coastal trade. This drove the Dutch Governor General, J.J. Rochussen, to issue a decree in February 1846 outlining Dutch terrestrial interests (as opposed to mere coastal control) over Borneo. This document provided a fait-accompli division of Borneo based on the flow of watersheds. This decree was essentially the blueprint that the Dutch subsequently negotiated with the British that resulted in the Anglo-Dutch Treaty of 1891.Resolution of the Governor-General of Netherlands India regarding the Dutch Possessions in Borneo, dated Buitenzorg-Batavia, 28 February 1846
The principal document determining the land border between Indonesia and Malaysia on the island of Borneo is the Border Convention or London Convention of 1891Convention between Great Britain and the Netherlands Defining the Boundaries in Borneo, 20 June 1891. which was signed in London between the United Kingdom and the Netherlands, the two relevant colonial powers of that time, on 20 June 1891. Subsequent agreements between the colonial powers in 1915Agreement between the United Kingdom and the Netherlands relating to the Boundary between the State of North Borneo and the Netherland Possessions in Borneo, 28 September 1915. and 1928Convention between His Majesty in respect of the United Kingdom and Her Majesty the Queen of the Netherlands respecting the Delimitation of the Frontier between the States in Bomeo under British Protection and Netherlands Territory in that Island, 26 March 1928. fine-tuned the border further. Much of the fine-tuning of the border concerned the Jagoi - Stass region in western Borneo, which, after negotiations stalled in 1930, was not yet considered definitive.Departement van Kolonien. Openbaar Verbaal No. 85, 1 April 1922, Algemeen Rijksarchief (ARA); Openbaar Verbaal No. 86, 22 May 1922; Openbaar Verbaal No. 13, 29 June 1922, ARA; Openbaar Verbaal No. 7, 8 August 1924, ARA; Openbaar Verbaal No. 8, 7 September 1926, ARA; Openbaar Verbaal No. 11, 16 August 1930, ARA. The treaty and various agreements were subsequently adopted by Indonesia and Malaysia as successor states. The unresolved status of the maritime boundary in the Celebes Sea, which has been the source of recent Malaysia-Indonesia boundary disputes over Ligitan, Sipadan and Ambalat, is partly due to the fact that most maritime boundaries were never demarcated by the colonial powers, which focused primarily on land borders.
The convention states that the eastern end of the border would start at the 4° 10' North latitude,Convention of 1891, Article I. proceeding westward across the island of Sebatik off the coast of Sabah near Tawau town, bisecting it.Convention of 1891, Article IV: From 4° 10' North latitude on the east Coast the boundary-line shall be continued eastward along that parallel, across the Island of Sebittik: that portion of the island situated to the north of that parallel shall belong unreservedly to the British North Borneo Company, and the portion south of that parallel to the Netherlands. The border then crosses the water channel between Sebatik and the mainland and travels up along the median line of the Tambu and Sikapal channels until the hills which form the watershed between the Simengaris (in Indonesia) and Serudung (in Malaysia) rivers.Agreement of 1915, (2) Starting from the boundary pillar on the West coast of the island of Sibetik, the boundary follows the parallel of 4° 10' North latitude westward until it reaches the middle of the channel, thence keeping a mid-channel course until it reaches the middle of the mouth of Troesan Tamboe. (3) From the mouth of Troesan Tamboe the boundary line is continued up the middle of this Troesan until it is intersected by a similar line running through the middle of Troesan Sikapal; it then follows this line through Troesan Sikapal as far as the point where the latter meets the watershed between the Simengaris and Seroedong Rivers (Sikapal hill), and is connected finally with this watershed by a line taken perpendicular to the centre line of Troesan Sikapal. The border travels generally northwestward towards the 4° 20'N, and then generally westwards but accommodating the watershed, although the Pensiangan, Agisan and Sibuda rivers are allowed to intersect the border. The border then follows the line of ridges along the watershed between major rivers following northwards into the South China Sea, and those flowing eastwards, southwards and westwards into the Celebes Sea, Java Sea and Karimata Straits until Tanjung Datu at 109° 38'.8 E 02° 05'.0 N in the western extremity of Sarawak. The watershed is however not followed in a short stretch southwest of Kuching between Gunung Api at 110° 04'E and Gunung Raja at 109° 56'E where the border follows streams, paths, crests and straight lines which are marked by boundary markers and pillars.
On 26 November 1973, a memorandum of understanding was signed between Indonesia and Malaysia for the joint survey and demarcation of their common land border. Work began on 9 September 1975 and was completed in February 2000. As of 2006, a total of 19 memoranda of understanding with 28 maps had been signed between the two countries pertaining to the survey and demarcation of the border covering a distance of 1,822.3 km of the 2,019.5 km border.
Maritime boundaries
The maritime boundaries between Indonesia and Malaysia are located four bodies of water, namely the Strait of Malacca, Strait of Singapore, South China Sea and Celebes Sea. The territorial seas of both countries (both claim a territorial sea) only meet in the Straits of Malacca and Straits of Singapore. Territorial sea boundaries also exist at the continuation of both ends of the land boundary between the two countries in Borneo. Only continental shelf boundaries have been agreed to in the South China Sea while the continental shelf boundary in the Celebes Sea has not been determined at all.
Straits of Malacca and Straits of Singapore Continental shelf and territorial sea agreements
The continental shelf and territorial sea boundaries generally runs along the median line between the baselines of the two countries. Indonesia and Malaysia both agreed to a continental shelf boundary in 1969 (signed on 27 October 1969)(map ) and a territorial sea boundary in 1970 (signed on 17 March 1970). (map ) The two countries together with Thailand entered to an agreement on 21 December 1971 established a common maritime tripoint as well as extended the continental shelf boundary between Indonesia and Malaysia from the northern terminus defined in the 1969 agreement to meet the tripoint in a straight line (see table below). (map )
Both the continental shelf boundary and territorial sea boundary generally follow the equidistant line between the baselines of the two countries. The continental shelf and territorial sea boundaries are generally one and the same line with the same turning points except for one turning point of the territorial sea boundary known as "Turning Point 6" which does not apply to Malaysia, with the Malaysian territorial sea boundary running directly from Turning Point 5 to Turning Point 7, which coincides with the continental shelf boundary as defined by the 1969 apgreement. This phenomenon creates a small triangle of sea in the southern part of the Straits of Malacca which forms part of the Indonesian continental shelf but not part of the country's territorial sea.
Malaysia's 1979 map
The continental shelf and territorial sea boundaries beyond the southern terminus of the 1969 and 1970 agreements have not been agreed to. The 1979 territorial sea and continental shelf map published by MalaysiaSee map reproduced by the Singapore Ministry of Foreign Affairs in the country's response in the International Tribunal of the Law of the Sea case concerning the reclamation of lands by Singapore in the Straits of Johor . shows a unilaterally drawn continental shelf/territorial sea boundary connecting the southern terminus of the 1969 continental shelf and 1970 territorial sea agreement between Indonesia and Malaysia with the Malaysia-Singapore border at the western entrance of the Straits of Johor. The boundary's southernmost turning point, namely Point 17, is inside Indonesia's baseline in the Riau Islands, giving the impression that Malaysia is claiming a slice of Indonesia's internal waters as part of its territorial sea. The boundaries on the 1979 map are not recognised by Indonesia nor Singapore.
The map also does not show the western Indonesia-Malaysia-Singapore tripoint, which should be located in this area. Indonesia and Singapore signed an agreement in 2009, extending their defined common boundary to a point where the two countries claim was as far westwards as they could go bilaterally. Tri-lateral negotiations would be necessary to define the tri-point and close the undefined boundary gaps.