 A third group is the Madurese, who inhabit the island of Madura off the northeast coast of Java, and have immigrated to East Java in large numbers since the 18th century.The Javanese comprise about two-thirds of the island's population, while the Sundanese and Madurese account for 20% and 10% respectively.The fourth group is the Betawi people that speak a dialect of Malay, they are the descendants of the people living around Batavia from around the 17th century.