Western Indonesia Indonesia Barat
Region
Top-down, left-to-right:Borobudur Temple,Bogor Palace,Pagaruyung Palace,Siak Palace,Palembang LRT,Jakarta skyline,Thai Pak Kung Temple,TarakanIslamic Centre
Country	Indonesia
Provinces	Aceh North Sumatra West Sumatra Riau Jambi South Sumatra Bengkulu Lampung Bangka Belitung Islands Riau Islands Jakarta West Java Central Java Special Region of Yogyakarta East Java Banten West Kalimantan Central Kalimantan South Kalimantan East Kalimantan North Kalimantan
Largest city	Jakarta
Other major cities	Surabaya Bandung Medan Semarang Palembang Batam Balikpapan Samarinda Pekanbaru
Area
• Total	854,164 sq mi (2,212,274 km2)
• Land	236.400 sq mi (612.274 km2)
• Water	620,000 sq mi (1,600,000 km2)
Population  (2022)
• Total	230.563.678
• Density	0.975308/sq mi (0.376568/km2)
Time zones	UTC+07:00 (Western Indonesia Time)
	UTC+08:00 (Central Indonesia Time)
Official language	Indonesian
Regional languages	Javanese Sundanese Malay Batak Minangkabau Dayak Banjarese Acehnese

Western Indonesia (Indonesian:Indonesia Barat;pronounced[ɪndoˌnes(i)jaˈbarat̪̚]) is one of the two main geographicalregions ofIndonesia, the other beingEastern Indonesia. It consists of21 provinces inJava,Kalimantan, andSumatra.Western Indonesia Time (Indonesian:Waktu Indonesia Barat, WIB;pronounced[ˌwak̚t̪uɪndoˌnes(i)jaˈbarat̪̚]) is seven hours ahead (UTC+07:00) of theCoordinated Universal Time (UTC), used in the islands ofSumatra,Java, and the western half ofKalimantan.^[1][2]

Western Indonesia has a land border withEast Malaysia to the North andPeninsular Malaysia to the West.

Military action by the Dutch launched on 20 July 1947 against areas controlled by the Indonesian republicans,Operation Product, resulted in the Dutch regaining control of West and East Java, the areas aroundMedan,Palembang andPadang inSumatra. TheUnited Nations called for a ceasefire, and negotiations between the two sides led to theRenville Agreement of January 1948, with a ceasefire along the "Van Mook Line", which connected the most advanced Dutch positions. The Dutch then established states in the areas they had reoccupied, includingEast Sumatra (December 1947),Madura andWest Java (February 1948),South Sumatra (September 1948) andEast Java (November 1948). The leaders of these regions then established theFederal Consultative Assembly.

A second Dutch military action,Operation Kraai, aimed at destroying the Republic, was launched on 18 December 1948. Despite recapturing the major cities ofJava, including the republican capital ofYogyakarta, and all ofSumatra exceptAceh in the far north, it triggered the protest resignation of the cabinets of theState of East Indonesia andPasundan (West Java) and theSultan of Yogyakarta from his position as regional head.

The main islands of Sumatra, Java, Madura, and Kalimantan lie on theSunda plate.Indonesia has relatively high tectonic and volcanic activities. It lies on the convergence between theEurasian,Indo-Australian,Pacific, andPhilippine Sea plate. TheSunda megathrust is a 5,500 km long fault located off southern coasts of Sumatra, Java andLesser Sunda Islands, where the Indo-Australian plate is thrusting northeastward towards the subducting Sunda plate. Tectonic movement in this fault is responsible for the creation of theSunda Trench, and mountain ranges across Sumatra, Java.^[3]Mount Merapi, located in the Java portion of the megathrust, is the most activevolcano in Indonesia and is designated as one of world'sDecade Volcanoes due to the hazard it poses to the surrounding populated areas.^[4]

Borneo is the third largest island in the world and the native vegetation was mostlyBorneo lowland rain forests although much of this has been cleared with wildlife retreating to theBorneo montane rain forests inland.Kalimantan and Sumatra, experience only slight differences in rainfall and temperature between the seasons, whereas others, such asNusa Tenggara, experience far more pronounced differences with droughts in the dry season, and floods in the wet. Rainfall in Indonesia is plentiful, particularly inWest Sumatra, Northwest Kalimantan,West Java.

Western Indonesia is composed of three main geographic units:Kalimantan,Java andSumatra.

Below are the top 13 provinces in Western Indonesia ranked by GDP in 2019:

Rank	Province	Region	GDP (in billionRp)	GDP nominal	GDP PPP
				(in billion$)	(in billion$)
-	Indonesia	South East Asia	16,073,257	1,136.72	3,329.17
1	Jakarta	Java	2,840,828	200.91	588.42
2	East Java	Java	2,352,425	166.37	487.27
3	West Java	Java	2,125,158	150.30	440.19
4	Central Java	Java	1,362,457	96.35	282.18
5	North Sumatra	Sumatra	801,733	56.70	166.06
6	Riau	Sumatra	765,198	54.12	158.51
7	Banten	Java	664,963	47.03	137.74
8	East Kalimantan	Kalimantan	653,677	46.23	135.40
9	South Sumatra	Sumatra	455,233	32.19	94.28
10	Lampung	Sumatra	360,664	25.51	74,71
11	Riau Islands	Sumatra	268,080	18.96	55.53
12	West Sumatra	Sumatra	246,423	17.42	51.01
13	Jambi	Sumatra	217,712	15.40	45.10

In 2012, the DMO was 24.72%. Starting from 2014, no low-grade coal exports are allowed, so theupgraded brown coal process that cranks up the calorie value of coal from 4,500 to 6,100 kcal/kg will be built inSouth Kalimantan andSouth Sumatra.^[6][7][8]Major Japanese factories are concentrated east of Jakarta with high concentrations inBekasi,Cikarang andKarawang,West Java.

Jakarta is the largest city and the onlymegacity in Indonesia, with a population of 10.70 million. As aprimate city, Jakarta is nearly four times larger than the second largest citySurabaya. Jakarta's status is unique compared to other cities in Indonesia, since it is technically aprovince with a city management. It is subdividied intofive administrative cities and an administrative regency, which are notself-governed (withoutmunicipal council norgovernment budget). All five of Jakarta'ssatellite cities also have passed one million mark in population, with the largest one beingBekasi.

The other largest cities byregion includeMedan (Sumatra, also the largest outside ofJava),Samarinda (Kalimantan).

Below are the populations of each provinces which make up the total population of Western Indonesia:

Indonesia recognizes only a single national language, and indigenous languages are recognized at the regional level, although policies vary from one region to another. For example, in theSpecial Region of Yogyakarta, theJavanese language is the region's official language along withIndonesian.^[9]The next most widely spoken regional languages in the country areSundanese, localMalay, andMinangkabau.There are hundreds of indigenous languages spoken in Indonesia. Most of them are locally used indigenous languages,^[10] a category of languages referring to those spoken at the local, regional level, spoken by a small number of people, ranging from a few to a few thousands of people. These include small languages such asBenggoi,Mombum andTowei.^{[11][page needed]} Other languages are spoken at the regional level to connect various ethnicities. For this reason, these languages are known as regionallingua francas (RLFs). According to Subhan Zein, there are at least 43 RLFs in Indonesia, categorized into two types: Malayic RLFs and Non-Malayic RLFs. The former refers to a group of regional lingua francas that are thought of as indigenised varieties ofMalay orIndonesian. These include such languages likeBanjar Malay among others. The latter refers to regional lingua francas that are not associated with Malay or Indonesian, likeIban.^{[12][11][page needed][a]}

The population numbers given below are ofnative speakers, excepting the figure for Indonesian, which counts its total speakers.

Religion was a census variable in the 1961, 1971, 1980, 1990, 2000, and 2010 and in various intercensal surveys. Being deemed divisive, the 1961 census data regarding religion was not published. In 1971, three groups ofChristians were recorded:Catholic,Protestant and other. The U.N. Demographic Yearbook 1979 only lists data collectively for all Christians. In the 2000 census, only Catholics and Protestants were available as categories.^[15]

Religious composition by ethnic group^[16]

• Regions of Indonesia
• Eastern Indonesia

• Simons, Gary F.; Fennig, Charles D. (2018)."Indonesia".Ethnologue: Languages of the World, Twenty-first edition. SIL International. Archived fromthe original on 26 June 2019. Retrieved20 September 2018.
• Zein, Subhan (2020).Language Policy in Superdiverse Indonesia. New York and London:Routledge.ISBN 9780367029548.

• Regions of Indonesia
• Subdivisions of Indonesia

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