Why did the dakota sioux start an uprising in 1862?

The Dakota Sioux War of 1862, also known as the Sioux Uprising, Dakota Uprising, the Sioux Outbreak of 1862, theDakota Conflict, the U.S.–Dakota War of 1862 or Little Crow's War, was an armed conflict between the United States and several bands of Dakota (also known as the eastern 'Sioux'). The origins of the uprising could be traced to a series of ill-advised treaties the Indians had signed in the 1850s. The first pacts were signed at Traverse des Sioux and Mendota in 1851. Collectively, the Sioux ceded almost 24 million acres of prime agricultural land, which was legally opened to white settlers three years later. The tribe agreed to part with the priceless territory in exchange for comparatively insubstantial amounts of cash and annuities

It was an armed conflict between the United States and several bands of Dakota 

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