Indonesia, called Dutch East Indies before the late 1940s, is a republic in Southeast Asia and Oceania, comprising 17,508 islands located between the Indian and Pacific Oceans. It includes about half of New Guinea (Earth's second largest island), more than half of Borneo (the fourth largest island), and all of Sumatra (the 6th largest island). The capital is Jakarta on the island of Java, the population center of the country. Bali, a fairly small island, is nevertheless an important cultural center. With a population of around 230 million people, Indonesia is the world's fourth most populous country, and has the world's largest population of Muslims. Within Borneo, Indonesia has a land border with Malaysia, and within New Guinea it has a land border with Papua New Guinea.
Indonesian history has been influenced by foreign powers drawn to its natural resources. Muslim traders brought Islam, and European powers fought one another to monopolize trade in the Spice Islands of Maluku during the Age of Discovery. Following three and a half centuries of Dutch colonialism, Indonesia secured its independence after World War II.
During the interwar period, the Empire of Japan "persuaded" the Netherlands to hand over the Dutch East Indies to them for a large sum of compensation with an underlying threat of force. The Japanese had done the same to the French Empire (which had been defeated and weakened during the Great War) by forcing them to hand over Indochina.
Indonesia was the site of two of history's most powerful volcanic explosions: Tambora, leading to the Year Without a Summer, and Krakatoa, both in the 19th century. These cataclysms were dwarfed by previous Yellowstone Supervolcano eruptions in prehistory, throwing up seven and forty times as much ash and lava in comparison. However, previous Yellowstone eruptions were not as forceful as Indonesia's Mount Toba, which obliterated itself, and nearly caused the extinction of the human species, around 70,000 BC.
Japan launched an attack and an invasion upon Indonesia on 12 January 1941, concurrently with an invasion of British Malaya and attacks upon American holdings Manila and Hawaii. By the end of 1941, the Dutch East Indies was falling, the Japanese having conquered a large number of the islands, from Borneo in the north to Lesser Sunda Islands in the south. Many believed it couldn't be held and would only be a matter of time before all the islands fell.
Indonesia was ruled by the Dutch East India Company until the Netherlands were conquered by Germany in 1940 during World War II. Indonesia itself was conquered by Japan. It continued to be ruled by Japan under the terms of the Peace of Cairo in 1944, despite the expectation that Japan would be stripped of most of its empire.