The History of Indonesia was shaped by its geographic position, its natural resources, the series of human migrations, contacts, economy and trade, conquests and politics. Indonesia is an archipelagic country of 17,508 islands (6,000 inhabited) stretching along the equator in South East Asia. The country's strategic sea-lane position fostered inter-island and international trade; trade has since fundamentally shaped Indonesian history. The area of Indonesia is populated by peoples of various migrations, creating a diversity of cultures, ethnicities, and languages. The archipelago's landforms and climate significantly influenced agriculture and trade, and the formation of states.

Fossilised remains of Homo erectus and his tools, popularly known as the "Java Man", suggest the Indonesian archipelago was inhabited by at least 1.5 million years ago. Austronesian people, who form the majority of the modern population, are thought to have originally been from Taiwan and arrived in Indonesia around 2000 BCE. From the 7th century CE, the powerful Srivijaya naval kingdom flourished bringing Hindu and Buddhist influences with it. The agricultural Buddhist Sailendra and Hindu Mataram dynasties subsequently thrived and declined in inland Java. The last significant non-Muslim kingdom, the Hindu Majapahit kingdom, flourished from the late 13th century, and its influence stretched over much of Indonesia. The earliest evidence of Islamised populations in Indonesia dates to the 13th century in northern Sumatra; other Indonesian areas gradually adopted Islam which became the dominant religion in Java and Sumatra by the end of the 16th century. For the most part, Islam overlaid and mixed with existing cultural and religious influences.