Indonesia–Malaysia border

Dutch and British Borneo

The Dutch saw Borneo as an outpost of Java and cared most for its south coast; the British saw it as a station on the route to China and wanted the north coast’s harbours. In 1842 James Brooke became ruler of Sarawak, which grew at the expense of Brunei, and in 1881 Britain chartered the North Borneo Company on land ceded by the sultans of Brunei and Sulu, over Dutch protests.^[1]

A commission set up in 1889 led to the London Convention of 1891, a compromise between the two powers’ claims. It split the island of Sebatik along the parallel of 4° 10′ N and then followed the main watershed of the principal rivers west to Tanjung Datu on the South China Sea; it was amended in 1915 and 1928 as the terrain became better known. Only two short sectors are marked on the ground. Elsewhere the line runs along low folded mountains under dense rain forest, reaching 7,084 feet near the Sabah–Sarawak–Kalimantan junction.^[1]

“The general picture is one of continuous and monotonous forest coverage.”^[1]

Confrontation

Indonesia replaced the Dutch in 1949. When Sarawak and North Borneo, renamed Sabah, joined Malaya to form Malaysia on 16 September 1963, Indonesia protested; a UN mission reported that a sizeable majority favoured the federation, but Indonesia rejected its report. By 1965, guerrilla operations from Indonesian territory had taken place along the frontier, though Indonesia officially claimed no part of the two states.^[1]

Ligitan and Sipadan

In 1998 the two countries asked the International Court of Justice to decide who owned the islands of Ligitan and Sipadan, off the eastern end of the border. Indonesia argued that the 1891 line continued out to sea; the Court found that the convention set no line east of Sebatik and that neither side had a treaty title. It weighed the two sides’ acts of administration instead: Indonesia cited naval patrols and its fishermen, Malaysia the regulation of turtle-egg collecting and lighthouses built in 1962 and 1963. On 17 December 2002 it ruled that the islands belong to Malaysia.^[2]