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 defence, transnational crimes, education, youth, culture and people-to-people contacts. Both Brunei and Indonesia have many common characteristic traits, these include common frames of reference in history, culture and religion. Their national languages; Indonesian language and Malay language are closely related. The majority of the population of both nations were of Austronesian ancestry or of the Malay race, with significant Malay culture shared among them. Both nations are Muslim majority countries, members of ASEAN and APEC, and also members of the Non-aligned Movement, and Organisation of Islamic Cooperation. Relations between Indonesia and Brunei has been established since 14th century or perhaps