In late 1553, Manuel da Nóbrega, the first Provincial of the Jesuits in Brazil, sent 13 Jesuits including Anchieta to climb the Serra do Mar to a plateau along the Tietê River that the Indians called "piratininga" (from Tupi "pira" "fish" + "tininga" "drying" – according to Anchieta, more than 12,000 fish could be found drying along the Tietê river floodplains after one of its customary floods). There the Jesuits established a small missionary settlement and celebrated Mass for the first time on 25 January 1554, date of the conversion of Saint Paul, according to tradition. That date is now celebrated as the founding of São Paulo. Anchieta and his Jesuit colleagues began their efforts to instruct the native people in the rudiments of Christianity and convert them, while also introducing basic education in other subjects. He taught Latin to the Indians, began to learn their language, Old Tupi, and started compiling a dictionary and a grammar. Their mission settlement, the Jesuit College of São Paulo of Piratininga, soon developed into a small population center.