Tiny state in Borneo, sandwiched between Sarawak and Sabah. After it was a big regional player a few hundred years back, Brunei became rich upon the discovery of Oil in the 1940s. For a period time the Sultan of Brunei was the richest person in the world.
Singapore
Singapore is an island nation located at the southern tip of the Malay Peninsula. At 704.0 sqkm (272 square miles), it is one of the few city-states in the world and the smallest country in Southeast Asia.