Brunei–Malaysia border which are defined by agreements, from west to east, are as follows: Brunei and Malaysia in an Exchange of Letters on 16 March 2009, agreed to affirm the five agreements. The two countries also agreed to use the watershed principle to determine the remaining undelimited portions of the border. Brunei's maritime boundary with Malaysia until the 100 fathom isobath was inherited from the Sarawak (Definition of Boundaries) Order in Council 1958 No 1518 and the North Borneo (Definition of Boundaries) Order in Council 1958 No 1517, both of which defined the boundary between Brunei on the one hand, and Sarawak
Geography of Malaysia districts. There are separate subdivisions for electoral districts for polling purposes. International borders between Malaysia and Indonesia, Thailand, Singapore and Brunei are defined mostly by geological features such as the Perlis River and Golok River between Malaysia and Thailand; Straits of Johor between Malaysia and Singapore; and Pagalayan Canal between Malaysia and Brunei. However, borders that extends to the seas are defined by agreements such as Straits Settlement and Johore Territorial Waters Agreement of 1927 which defines Malaysia and Singapore water borders. Malaysia's land borders are well established. The border with Thailand was established in 1909 when Siam ceded Kedah,