Claim: The Chapada das Mangabeiras is a mountain range in Central Brazil that runs northwest-southeast, separating the basin of the Tocantins River to the southwest from the upper basin of the Parnaiba River to the northeast and forming the boundary between Tocantins state and the states of Maranhão and Piauí.
Evidence: The Chapada das Mangabeiras is a mountain range in central Brazil. The range runs northwest-southeast, and separates the basin of the Tocantins River to the southwest from the upper basin of the Parnaiba River to the northeast. The range also forms the boundary between Tocantins state and the states of Maranhão and Piauí.