The Indonesian archipelago is the largest island complex in the world, stretching for more than 3,000 miles east to west. During the first millennium C.E., the islands of Java and Sumatra had developed into a society of advanced civilization, with goods being shipped overseas and navigable rivers bringing the Indonesian hinterland into touch with distant markets. From the seventh to 14th centuries, Buddhism flourished on the island of Sumatra. In eastern Java, Hinduism prevailed in the 14th century, and in 1364, the Hindu empire conquered most of what is now modern Indonesia and much of the Malay Archipelago. During the 12th century, Islam arrived in Indonesia, and replaced Hinduism in dominating Java and Sumatra by the end of the 16th century. In the 16th and 17th centuries, both Christian and Islamic proselytizing took place in the eastern archipelago, and both religions have large communities on these islands today. On the island of Bali, Hinduism endures. During the 17th century, Indonesia gradually became under control of the Netherlands, except for East Timor. which remained under the control of Portugal until 1975 and just gained its independence from Indonesia in 2000. Under Dutch rule for 300 years, Indonesia was developed into one of the Netherlands' richest colonies in the world.

Indonesia has the fourth largest population in the world, with a total of more than 224 million people. The island of Java is one of the most densely populated areas in the world, with more than 107 million people living in an area the size of New York state. Indonesia is composed of numerous related, but distinct, cultural and linguistic groups. The ethnic groups tend to be derived from the Malay ethno-linguistic groupings, including the Javanese, which make up almost half the population, as well as Sundanese, Madurese, coastal Malays, among others. There is also a substantial minority of European and North American expatriates living in Indonesia, as well as some people of Dutch extraction who are descendants of the colonists.