East Malaysia (Malaysia Timur), also known as Sabah, Sarawak and Labuan (Sabah, Sarawak dan Labuan) or Malaysian Borneo, is the part of Malaysia on the island of Borneo, the world’s third largest island. It consists of the Malaysian states of Sabah, closer to the Philippines than the west of the country, Sarawak in the west and the Federal Territory of Labuan. Labuan is an island in its small archipelago of the same name due north of Brunei; its closest land mass is with Sabah. It lies to the east of Peninsular Malaysia (West Malaysia), the part of the country on the Malay Peninsula. The two are separated by the South China Sea.

East Malaysia is less populated and overall less developed in its settlements than is West Malaysia, which contains Kuala Lumpur and Penang; its land mass, however, is larger and it has more of many natural resources including oil and gas reserves. City status award is restrained in the pan-regional style so reserved to Kuching, Kota Kinabalu, and Miri; Victoria, Labuan for example is an Offshore Financial Centre and major port. In ecology it has a significant proportion of the biodiverse Borneo lowland rain forests and Borneo montane rain forests.

SOURCE: https://en.wikipedia.org/wiki/East_Malaysia