The Portuguese had defeated Matamba in 1836, and had advanced to Kasanje by the middle of the century. Their actual influence, however, was quite limited due to the lack of people, money, and an efficient military. The Ambundu had opportunities to revolt or negotiate liberties. This changed at the end of the 19th century. European countries forced, out of economic, strategic, and nationalistic considerations, a tighter control over African territories. To protect their interests, the Portuguese sent a number of military expeditions into the areas, which they considered to be their colonies, and brought them under actual control. The last Ambundu tribe to be defeated were the NDembo. It took the Portuguese three years to subdue a NDembo revolt in 1910. In 1917 all of their territory was occupied, and became part of the Portuguese colony of Angola.