Santana de Parnaíba is a city and municipality in the state of São Paulo in Brazil. It is part of the Metropolitan Region of São Paulo. The population is 126,574 (2015 est.) in an area of 179.95 km². It was founded in 1625 on the banks of the Tietê River, by Susana Dias, an important Bandeirante (Brazilian pioneers) wife. The city can be considered one of the oldest in Brazil, playing an important role in the expansion and territorial delimitation of the country. Nowadays, the city holds the highest historical patrimony of the colonial era in Brazil, besides being in full development and being a reference in several areas such as education, security and health. The word Parnaíba means rocky river. The municipality contains and administers the 367 hectares (910 acres) Tamboré Biological Reserve, a strictly protected conservation unit.