Aside from rubber collection, violence in the Free State chiefly occurred in connection with wars and rebellions. Native states, notably Msiri's Yeke Kingdom, the Zande Federation, and Swahili-speaking territory in the eastern Congo under Tippu Tip, refused to recognise colonial authority and were defeated by the "Force Publique" with great brutality, during the Congo–Arab War. In 1895, a military mutiny broke out among the Batetela in Kasai, leading to a four-year insurgency. The conflict was particularly brutal and caused a great number of casualties.