Map - West Sumatra (Provinsi Sumatera Barat)

West Sumatra (Sumatra Barat; Sumatera Barat, Jawi: صوماتىرا بارات) is a province of Indonesia. It is located on the west coast of the island of Sumatra and includes the Mentawai Islands off that coast. The province has an area of 42,012.89 km2, with a population of 5,534,472 at the 2020 census. The official estimate at mid 2021 was 5,580,232. West Sumatra borders the Indian Ocean to the west, as well as the provinces of North Sumatra to the north, Riau to the northeast, Jambi to the southeast, and Bengkulu to the south. The province is subdivided into twelve regencies and seven cities. It has relatively more cities than other provinces outside of Java, although several of them are relatively low in population compared with cities elsewhere in Indonesia. Padang is the province's capital and largest city.

West Sumatra is home to the Minangkabau people, although the traditional Minangkabau region is actually wider than the province's boundaries, covering up to the southern region of North Sumatra, the western region of Riau, the western region of Jambi, the northern region of Bengkulu, and Negeri Sembilan in Malaysia. Another native ethnic group is the Mentawai people, who inhabit the western islands of the same name. Islam is a predominant religion in the province, with about 97.4% of the total population.

West Sumatra was the centre of the Pagaruyung Kingdom, founded by Adityawarman in 1347. The first European to come to the region was a French traveler named Jean Parmentier who arrived around 1523. The region was later colonised by the Dutch Empire and became a residency named Sumatra's West Coast (Sumatra's Westkust), whose administrative area included the present-day Kampar Regency in Riau and Kerinci Regency in Jambi. Before becoming a province in 1957, West Sumatra was a part of the province of Central Sumatra (1948–1957), alongside Riau, Jambi, and the Riau Islands.

West Sumatra is known by the name Bumi Minangkabau (Land of Minangkabau), as it is the home and origin of the Minangkabau people. The Minangkabau name comes from two words namely, Minang (win) and Kabau (cattle). The name is associated with a Minangkabau legend known as Tambo. From the Tambo, it is said that at one time there was a foreign kingdom (usually interpreted as the Majapahit Empire) which came from the sea and would conquer what is now West Sumatra. To prevent fighting in the region, the local people propose a cattle race competition with the foreign forces. The foreign forces agreed and sent a large and aggressive cattle to the competition, while the local community sent a cattle calf who was still breastfeeding to the competition. In the competition, the cattle calf who was still breastfeeding thought the large and aggressive cattle was the mother. So the calf immediately ran towards the large and aggressive cattle to find milk until he tore apart the big cattle's stomach. The victory inspired the local people to use the name Minangkabau, which comes from the phrase "Manang kabau" (winning cattle). The story of the Tambo is also found in the Hikayat Raja-raja Pasai which also mentions that the victory made the country that was previously named Pariangan changed to the name Minangkabau. Furthermore, the use of the name Minangkabau is also used to refer to a nagari (village), namely the Nagari Minangkabau, which is located in Sungayang District, Tanah Datar Regency.

In the historical record of the Majapahit Empire, Nagarakretagama which dated from 1365, also mentioned the name Minangkabwa as one of the Malay countries that has been conquered by the Majapahit. Likewise in the Ming Chronicles from 1405, there was the royal name of Mi-nang-ge-bu of the six kingdoms who sent messengers facing Yongle Emperor in Nanjing. On the other hand, the name Minang (Minanga kingdom) itself has also been mentioned in the Kedukan Bukit inscription dated from 682 which is written in Sanskrit. In the inscription, it was stated that the founder of the Srivijaya Empire named Dapunta Hyang departed from a place called Minānga. Some experts who refer to the source of the inscription suspects that the 4th line words (... minānga) and the 5th line words (tāmvan ...) are actually incorporated, so that they become mināngatāmvan and are translated as the meeting point of twin rivers. The twin river is supposed to refer to the meeting of two sources of the Kampar River, namely the Kampar Kiri River and the Kampar Kanan River. But this hypothesis is denied by the Dutch indologist Johannes Gijsbertus de Casparis, which proves that tāmvan has nothing to do with "meeting point", because these can also be found in other Srivijaya relics.