Most of the state is in Brazil's Central Highlands; only the very north is in the Coastal Plain. A spine of mountains separates this state from Ceará to its east. The west boundary is the Paranaíba river which extends a narrow band of lowland nearly to the southern border.
In common with Brazil generally
Teresina, the capital, has about 700,000 city residents and just over a million in the metropolitan area. It sits at the fall line on the Paranaíba. Its old governor's residence is named the Palace of Karnak.All the pre-Columbian speakers belonged to groups that Joseph Greenberg collectively calls Amerindian. There are no surviving speakers in Piauí so extraopolation back from the present is impossible. During the colonial era Tupi served as a lingua franca along the coast.
north
east of the north of the state
east of the center of the state
south
west
(1) Nordeste in Portuguese.
(2) Officially Brasil since the late 19th century.