Final answer:
Brazil speaks Portuguese due to the Treaty of Tordesillas in 1494 which allocated the region to Portugal, leading to Portuguese becoming the dominant language and influencing the culture through plantation agriculture and the Catholic religion.
Step-by-step explanation:
The reason Brazil speaks Portuguese can be traced back to the colonial era, particularly due to the Treaty of Tordesillas in 1494. This treaty, which was influenced by the Catholic Church, sought to resolve territorial disputes between Spain and Portugal. As a result, a line of demarcation, known as the Tordesillas Line, was set, granting Brazil to Portugal. Hence, the Portuguese language and Catholicism became deeply ingrained in Brazilian culture.
Unlike the Spanish territories, which were rich in precious metals, the Portuguese in Brazil primarily engaged in the exportation of brazilwood and plantation agriculture, resulting in a societal dependence on African slave labor.
Despite the initial lack of interest from the Portuguese in Brazil, the attempt by French Huguenots to establish a colony there prompted Portugal to pay closer attention to their South American possession, leading to the development of sugar plantations and the increased import of African slaves.