Map of Indonesia
Indonesia is a multicultural country dominated by Javanese. Other major parts are Sumatra, Borneo (Kalimantan), Celebes (Sulawesi), Maluku, Bali, West Timor and West Irian/Papua, most of which are home to different ethnicities. The majority of Indonesia follows Islam, but Bali for example is predominantly Hindu, Maluku has many Catholics and Sulawesi and West Papua many Protestants. About 4% of the Indonesians are of Chinese descent and practice Buddhism. This group controls a significant portion of the economy with its international ties to the wider region, leading to anti-Chinese resentment whenever a crisis breaks out.
Indonesia declared independence from the Netherlands in 1945, after having been occupied by Japanese forces since 1942 and Dutch rule since 1602. The Dutch were not prepared to give up on resource-rich Dutch East Indies, and sent a military intervention force to quell the rebellion. A dirty war was the result with many atrocities committed by both sides. The UN ordered the Dutch to end the conflict in 1949 after which Indonesian independence was recognised.
Rebel leader Sukarno became the first president and led the country during the first hard years. Continuing economic hardships and authoritarian rule led to an attempted coup in 1965, which in turn led to an anti-communist purge during which at least half a million Indonesians were killed by the military. General Suharto took control of the government in 1968 and would continue authoritarian rule until 1998.
Widespread protests in 1998 led to the Reformasi, a reform to democracy. It was the year of the Asian Financial Crisis, during which Indonesia suffered from capital flight and high inflation. The new government was able to stabilise the situation, grant independence to East Timor, which had been occupied since 1974, and thanks to the high commodity prices achieve considerable economic growth.
Currency
Java had its own Rupee in the 18th century due to its trade links with India. This Rupee was worth 1.5 Gulden, which was inflated because the silver content was only 10% higher than that of the Gulden. Because of this similarity, the Gulden was named Rupiah in local language and formed the basis of Indonesia's national currency.
The Japanese occupiers renamed the Gulden to Rupiah in 1944. After WW2, the unrecognised Republic of Indonesia continued this currency which was debased heavily due to excessive money printing. The Dutch tried to restore order and restore a new Gulden, named NICA Gulden (but at par with homeland Gulden) in 1946 at a rate of 33 Rupiah per Gulden. After Indonesian independence this NICA Gulden, though initially unpopular, was used as the basis for a new Indonesian Rupiah in 1951 because it was much more stable. The Rupiah had an exchange rate of 7.6 Rp/$ for exports and 11.4 Rp/$ for imports, where Dutch Guldens were tied to Bretton Woods at a rate of 3.8 NLG/$ at that time.
From 1960 the Rupiah lost value very quickly to 5000 Rp/$ in 1965, after which it was replaced by a new Rupiah at 1000:1. Its value continued to fall until Suharto's new policies stabilised its value to 415 Rp/$ in 1970. This rate held for around a decade after which chronic inflation eroded more value. In 1998 the rate dropped from 2500/$ to 15,000/$ due to the Asian Financial Crisis and Indonesia's political instability. After stabilising to around 10,000/$ it started falling again since 2014 due to low oil prices to 13,000/$.
A 1000:1 revaluation was announced recently but no implementation date has been given.
A separate Rupiah circulated in West Irian (West Papua) from 1962 to 1971. It replaced the Netherlands New Guinea Gulden at par and was replaced by the Indonesian Rupiah 9 years later at a rate of 18.9 Rp per West Irian Rupiah.
Another Rupiah circulated briefly on the Riau Archipel in 1962. This one replaced the Malaya & British Borneo Dollar at par before the region was fully integrated into Indonesia.
Coins
The first Rupiah coins were minted in Utrecht and issued in 1952. These coins became worthless by 1960 and no coins were used for a decade. The New Rupiah was unstable at the start and only banknotes were used until a new coin series was introduced in 1970. Updates and higher denominations were introduced in 1994 and 1999. Current circulation coins are 100, 200, 500 & 1000 Rp.
West Irian had its own currency and coins from 1962 until 1971. These aluminium coins are pretty rare and feature a portrait of president Sukarno.
https://en.numista.com/catalogue/indonesie-1.html