East Malaysia is 50% bigger than Peninsular Malaysia at , comparable with South Dakota or Great Britain. East Malaysia contains the five highest mountains in Malaysia, the highest being Mount Kinabalu at 4095 m, which is also the highest mountain in Borneo and the 10th highest mountain peak in Southeast Asia. It also contains the two longest rivers in Malaysia – Rajang River and Kinabatangan River. Banggi Island in Sabah and Bruit Island in Sarawak are the two largest islands that are located entirely within Malaysia. The largest island is Borneo, which is shared with Indonesia and Brunei. The second largest island
Brunei–Indonesia relations Indonesia established diplomatic relations with Brunei Darussalam on 1 January 1984. Brunei Darussalam was recognised by Jakarta on independence in 1984, with Indonesia dropping any claims on the Sultanate in the process. Indonesia also supported Brunei membership to ASEAN in 1984. Brunei has been a popular destination for Indonesian workers. As per 31 August 2012, there is around 58,000 Indonesian citizens are staying and working in Brunei. Bilateral trade volume in 2011 reached around US$1.1 billion, coupled with around 3,500 Indonesian products in Brunei's market. In line with Brunei's economic diversication policy, the two countries are seeking to enhance co-operation