Under the Dutch rule, the development of an communal educational and political system started. Together with the islam was is formed the base the national awakening. The islamic organisation Sarekat Islam became the channel for the suppressed indignancy about foreign rule. In 1916, a small riot broke out in Jambi. Aceh was scared by riots in 1918-1919, in those same years, the Minangkabau founded a radical islamic movement.
In 1926 the Indonesian Communist party (PKI) started a revolution which was bound to fail, but it were the Minangkabau which formed the biggest part of this party. In 1917 the Jonge Sumatranen Bond (Union of Young Sumaterans) was formed bu the first generation which had Dutch education. They were supported by Minangkabau civil servants, teachers and traders.
In the 1920's the Toba Batak-students founded their own union. Against 1926 these two groups unified into the Indonesian Student Movement. Mohammah Hatta (the later vice-President) and Soetan Shahrir (first prime-minister of Indonesia), both from Sumatera, were very important to the formation of national awakening in Indonesia.
Even more important was the role of Sumatera in the development of national literature. Since Malay always has been the most important written language on the island, this was in contrary with the Jawanese and the Sundanese on Jawa. When Malay was adapted as Bahasa Indonesia, the language of the nationalism, this brought the least trouble to the island, the first writers that wrote modern literair pieces were virtually all from Sumatera.
In the early 1920's the political activists Mohammad Yamin, Sanusi Pane and Mohammad Hatta were the first to use Malay with a modern character. The prince of Langkat, Amir Hamzah, and the revolutionair Chairil Anwar wrote the most nice Indonesian poets in the 1930's and 1940's. The developement of the Indonesian roman in 1920 and 1930's was almost a Minangkabau matter.
The Japanese invasion, March 1942, caused more commotion on Sumatera than on Jawa. Aceh helped the Japanese a little by organising an armed revolt against the Dutch, who wanted to end the reign of the uleebalang.
In the first place the Japanese suppresses all nationalistic activities, but they gave nationalists access to the media, for mobilising people for war-purposes. At the end of the war, two rivaling elites were opposing eachother, the nationalists and the traditionalists.

Image  Drilling for oil

In 1945 the Japanese supported the idea of an independent Sumatera, and theu founded a college of advice without any real power and a secretary in Bukittinggi. In 1947 the Dutch, which came back, the districts of Eastern Sumatera and Southern Sumatera. The year after, they encouraged to create a coordinating organisation for those districts, but that didn't get much support. The Sumaterans had decided in the 1920 that they could bring together their many different ethnical groups by national level only.
Three days after Hiroshima, independence was called out in Jakarta, but the revolution on Sumatera only started in Octobre, when the allied forces acknowledged the Japanese surrender. Young activists, some with military training, first fought against the Japanese for weapons, and after that against the English which occupied parts of Medan, Padang and Palembang. At the end they fought the Dutch, which replaced the English at the end of 1946.
Most violence was internal. In Aceh, the uleebalang were overthrown by an islamic coalition in December 1945, after a bloody civil war. Three months later the Malay sultans of the eastern coast and the raja's of Simalungun were also overthrown. These sponteaneous movements lead to the downfall of the central power, especially in Eastern Sumatera, where paramiliatary groups posed themselves above the law. When the Dutch occupied the plantation areas around Medan and the oil-installations around Palembang in 1947, these armed groups fought with eachother in Tapanuli.
Sumatera was far from integrated politically and economically when the revolution ended in 1950 with the transfer of sovereignty to Indonesia. Every former residence had it's own military power, which turned to civil life with aversion, thought they could demand power and to play a role in the republic. The first crisis after the independence occured in Aceh, when the muslems refused to cooperate with the Christian Batak province in Northern Sumatera.
They accused the Indonesian government of not calling out an islamic state. In 1953 Aceh revolted against Jakarta. They declared theyr province a part of Dar al-Salam (the islamic world). Army units from Jawa soon occupied Acehnese cities, but the hinterlands were held by the rebels, which held until 1959, when a peace treaty was signed.
Aceh was named an autonomous province. Meanwhile, military leaders of the Toba Batak and Minangkabau joined the national politicians which were unhappy about the centralism, corruption and pro-communist government. Together they formed the PRRI (Revolutionairy Government of the Indonesian Republic) in February 1958.
The central government reacted with bombardments on Padang and Bukittinggi and sent a big force from Jawa. The fightings ended within six months, but Western Sumatera left it was only an occupied province. Where the Sumaterans were over-represented, now they were under-represented.
In 1966, President Suharto came to power. Under his 'Orde Baru'the regional disputes were eased. In the first place he had an anti-communist government and a free market is encouraged, things the PRRI liked. The second point was the fact that the government took care of building roads, supplying electricity, schools, hospitals and other infrastructural needs which improved the economic condition.
The big multi-ethnic provinces were dissolved, except Northern Sumatera (the former Eastern Sumatera and Tapanuli), and was forced back to the old borderd of the Dutch regencies. If any bad signs are heard about the nowadays pusat (the Indonesian capital), then that's not more than common for many places in Indonesia.