While East Malaysia is relatively less developed than West Malaysia, it has, notably, far more natural resources including large oil and gas fields.
Sarawak contains the Mulu caves within the Mulu national park; among these is the limestone cave with the largest chamber in the world, Sarawak chamber. The Mulu national park was declared a World Heritage site in 2001.
Both Sabah (formerly British North Borneo) and Sarawak were separate British colonies from Malaya, and did not become part of the Federation of Malaya in 1957. However, both voted to become part of the new Federation of Malaysia in 1963.
As states of the Federation, Sabah and Sarawak retained a higher degree of autonomy than the other states in West Malaysia. For example, they have separate immigration controls, and even Malaysian citizens from West Malaysia require passports when visiting East Malaysia.
The island of Labuan was part of Sabah until 1984, when it was made a separate Federal Territory, administered by the federal government. Its special status allowed it to become an offshore finance centre, with its own separate tax system and customs.