Among the most powerful and dominant tribes were the Dakota or Sioux, who occupied large amounts of territory in the Great Plains of the Midwest. The area of the Great Sioux Nation spread throughout the South and Midwest, up into the areas of Minnesota and stretching out west into the Rocky Mountains. At the same time, they occupied the heart of prime buffalo range, and also an excellent region for furs they could sell to French and American traders for goods such as guns. The Sioux (Dakota) became the most powerful of the Plains tribes and the greatest threat to American expansion.