São Tomé is an island of the Gulf of Guinea, discovered by the Portuguese in the 15th century. It was uninhabited at the time, but Portuguese settlers used the island as a center of the slave trade, and there was a need for slaves in the island. Since both parties needed to communicate, a pidgin was formed. The substrate languages were from the Bantu and Kwa groups. This pidgin then became fixed (creolized) as it became the mother language of children born from Portuguese men and African women slaves. Mixed marriages were then encouraged by the Portuguese Crown, for the sake of settlement.
Later because of Dutch and French pressure to gain the island, many Portuguese settlers left. Children of Portuguese and black women were, eventually, not considered African or slaves; some were considered full right Portuguese citizens. Those mixed-raced that did not have the status of Portuguese, those with darker skin, often gained a "forro" designation, because their Portuguese fathers did not want to enslave their children. The São Tomean Creole is mostly known as "Forro", the language of the freed slaves or Crioulo Santomense, not to be confused with São Tomean Portuguese (a variety and dialect of Portuguese in São Tomé and Príncipe). Portuguese is the main language for children until their early 20s, when they relearn Forro. The rich São Tomean culture also preserves a unique mixture of Portuguese and African cultures.