Java (Indonesian: Jawa) is an island of Indonesia. With a population of 136 million, it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. Much of Indonesian history took place on Java; it was the centre of powerful Hindu-Buddhist empires, Islamic sultanates, the core of the colonial Dutch East Indies, and was at the centre of Indonesia's campaign for independence. The island dominates Indonesian social, political and economic life.
Formed mostly as the result of volcanic events, Java is the 13th largest island in the world and the fifth largest island in Indonesia. A chain of volcanic mountains forms an east-west spine along the island. It has three main languages, though Javanese is dominant and is the native language of 60 million people in Indonesia, most of whom live on Java. Most residents are bilingual, with Indonesian as their first or second language. While the majority of the people of Java are Muslim, Java has a diverse mixture of religious beliefs, ethnicities and cultures.
The island's exceptional fertility and rainfall allowed the development of wet-field rice cultivation, which required sophisticated levels of cooperation between villages. Out of these village alliances, small kingdoms developed. The chain of volcanic mountains and associated highlands running the length of Java kept its interior regions and peoples separate and relatively isolated.[9] Before the advent of Islamic states and European colonialism, the rivers provided the main means of communication, although Java's many rivers are mostly short. Only the Brantas and Sala rivers could provide long-distance communication, and thus their valleys supported the centres of major kingdoms.
With a combined population of 136.5 million in the 2010 census and at current growth rates, 139 million combined in 2011, it is the most populous island in the world and is home to 57% of Indonesia's population.At 1,062 people per km² in 2010 it is also one of the most densely-populated parts of the world. Though little population growth is registered in Central Java, East Java, and Yogyakarta, these regions have higher birth rates than one would assume due to mass emigration to the Western side of Java, Sumatra, Borneo, and Papua. Approximately 45% of the population of Indonesia is ethnically Javanese, Sundanese make a large portion of Java's population as well. The dense Western third of the island (West Java, Banten, and DKI Jakarta) has an even higher population density exceeding 1,400 per km2 and is taking up the lion's share of population growth of Java.