Island, Malay Archipelago. Bounded by the South China Sea, the Sulu and Celebes seas, the Makassar Strait, and the Java Sea, it is the third largest island in the world, measuring about 292,000 sq mi (755,000 sq km). The northern part includes the Malaysian states of Sabah and Sarawak and the sultanate of Brunei; the southern section (Kalimantan) forms part of Indonesia. Borneo is mountainous and largely covered in dense rainforest; its highest point is Mount Kinabalu, at 13,455 ft (4,101 m). Much of it is drained by navigable rivers, including the Rajang, which are the principal lifelines of trade and commerce. It is mentioned in Ptolemy's Guide to Geography (c. AD 150); Roman trade beads give evidence of an earlier civilization. Brahman and Buddhist images in the Gupta style indicate the influence of Indians who apparently arrived in the 5th century. With the arrival of Islam in the 16th century, various Muslim kingdoms were founded, some of which owed allegiance to Java. Around the same time, the Portuguese, followed by the Spanish, set up trading stations. In the early 17th century the Dutch broke the Portuguese-Spanish monopoly, but they in turn had to deal with newly established British interests. After World War II, Sarawak and North Borneo (later Sabah) became British crown colonies. Strong nationalist sentiment emerged in Dutch Borneo, and sovereignty passed to Indonesia in 1949. The British relinquished Sabah and Sarawak to the Malaysian federation in 1963, while Brunei became independent in 1984.