The Basque people are an ethnic group indigenous to a region known as the Basque Country, which spans the border between northern Spain and southwestern France. Catalina de Erauso was a Basque person, and San Sebastian resides within the Basque Country. This heritage is very important within the Spanish colonies, as Erauso made friendships based on shared identity and was, on several occasions, defended by Basqueros (Basque people) even when they were strangers. These interactions highlight the shared ethnic identity and solidarity within this group while also showing that the binary distinction between Spanish and Indigenous people in South America that Erauso occasionally makes is not wholly accurate: Each side contains differing groups within itself.

The encomienda was a labor system instituted by the Spanish crown during the early colonization of the Americas and the Philippines. Under this system, Spanish settlers (encomenderos) were granted the right to extract labor and tribute from Indigenous communities. In return, the encomenderos were expected to religiously convert the Indigenous people. This system was an essential feature of the world in which Erauso lived, and it characterized the Spanish conquest of the Americas. It also defined the social mobility offered to Spaniards, as early settlers were able to gain incredible wealth through an encomienda—opportunities that were not often available to those of modest birth back in Spain.