São Paulo (Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC as an alpha global city, São Paulo is the most populous city proper in the Americas, the Western Hemisphere and the Southern Hemisphere, as well as the world's 4th largest city proper by population.

The region of modern-day São Paulo, then known as Piratininga plains around the Tietê River, was inhabited by the Tupi people, such as the Tupiniquim, Guaianás, and Guarani. Other tribes also lived in areas that today form the metropolitan region.

The Portuguese village of São Paulo dos Campos de Piratininga was marked by the founding of the Colégio de São Paulo de Piratininga on 25 January 1554. The Jesuit college of twelve priests included Manuel da Nóbrega and Spanish priest José de Anchieta. They built a mission on top of a steep hill between the Anhangabaú and Tamanduateí rivers.

They first had a small structure built of rammed earth, made by Native Indian workers in their traditional style. The priests wanted to evangelize these Indians who lived in the Plateau region of Piratininga and convert them to Christianity. The site was separated from the coast by the Serra do Mar mountain range, called "Serra Paranapiacaba” by the Indians.

The college was named for a Christian saint and its founding on the feast day of the celebration of the conversion of the Apostle Paul of Tarsus. Father José de Anchieta wrote this account in a letter to the Society of Jesus:

The settlement of the region's Courtyard of the College began in 1560. During the visit of Mem de Sá, Governor-General of Brazil, the Captaincy of São Vicente, he ordered the transfer of the population of the Village of São Bernardo do Campo to the vicinity of the college. It was then named "College of St. Paul Piratininga". The new location was on a steep hill adjacent to a large wetland, the Várzea do Carmo. It offered better protection from attacks by local Indian groups. It was renamed Vila de São Paulo, belonging to the Captaincy of São Vicente.

For the next two centuries, São Paulo developed as a poor and isolated village that survived largely through the cultivation of subsistence crops by the labor of natives. For a long time, São Paulo was the only village in Brazil's interior, as travel was too difficult for many to reach the area. Mem de Sá forbade colonists to use the Caminho do Piraiquê (Piraiquê Path) and today known as Piaçaguera, because of frequent Indian raids along it.

On 22 March 1681, Luís Álvares de Castro, the Second Marquis de Cascais and donee of the Captaincy of São Vicente, moved the capital to the village of São Paulo (see Timeline of São Paulo), designating it the "Head of the captaincy". The new capital was established on 23 April 1683, with public celebrations.

According to Wikipedia