Brunei , officially the Nation of Brunei, the Abode of Peace (Malay: Negara Brunei Darussalam, Jawi: نڬارا بروني دارالسلام‎), is a country located on the north coast of the island of Borneo in Southeast Asia. Apart from its coastline with the South China Sea, the country is completely surrounded by the Malaysian state of Sarawak. It is separated into two parts by the Sarawak district of Limbang. Brunei is the only sovereign state completely on the island of Borneo; the remainder of the island's territory is divided between the nations of Malaysia and Indonesia. Brunei's population was 428,963 in 2018. The government is an absolute monarchy under the sovereign rule of Sultan and Yang di-Pertuan, which implements a combination of English common law and sharia law, as well as direct general Islamic practices. At the peak of the Bruneian Empire, Sultan Bolkiah (reigned 1485–1528) is alleged to have had control over most regions of Borneo, including modern-day Sarawak and Sabah, as well as the Sulu Archipelago off the northeast tip of Borneo, and the islands off the northwest tip of Borneo. Claims also state that they had control over Seludong ("Kingdom of Maynila" to the local rulers of Maynila; where modern-day Manila now stands) but Southeast Asian scholars believe this refers to a settlement Mount Selurong in Indonesia. For political reasons, the historical rulers of Maynila maintained close cognatic ties through intermarriage with the ruling houses of the Sultanate of Brunei, but Brunei's political influence over Maynila is not considered to have extended to military or political rule. Intermarriage was a common strategy for large thalassocratic states (maritime states) such as Brunei to extend their influence, and for local rulers such as those of Maynila to help strengthen their family claims to nobility. The maritime state of Brunei was visited by Spain's Magellan Expedition in 1521 and fought against Spain in the 1578 Castilian War. During the 19th century, the Bruneian Empire began to decline.