Africans were transported by Portuguese slave traders to Spanish America starting in the early 16th century. Offspring of European Spaniards and African women resulted early on in mixed-race children, termed Mulattos. In Spanish law, the status of the child followed that of the mother, so that despite having a Spanish parent, their offspring were enslaved. The label Mulatto was recorded in official colonial documentation, so that marriage registers, censuses, and court documents allow research on different aspects of mulattos’ lives. Although some legal documents simply label a person a Mulatto/a, other designations occurred. In the sales of casta slaves in 17th-century Mexico City, official notaries recorded gradations of skin color in the transactions. These included "mulato blanco" or "mulata blanca" (white mulatto), for light-skinned slave. These were usually American-born ("criollo") slaves. Some said categorized persons i.e.m 'mulata blanca.' used their light skin to their advantage if they escaped their unlawful and brutal incarceration from their criminal slave owners, thus 'passing' as free persons of color. "Mulatos blancos" often emphasized their Spanish parentage, and considered themselves and were considered separate from "negros" or "pardos" and ordinary mulattos. Darker mulatto slaves were often termed "mulatos prietos" or sometimes "mulatos cochos". In Chile, along with "mulatos blancos", there were also "españoles oscuros" (dark Spaniards).