High Quality Content by WIKIPEDIA articles! Ecuador`s ethnic groups descend from Spanish colonizers and South American Indians; indeed, the relationship between the two groups has defined Ecuador`s subsequent pattern of ethnicity. The mix of these groups created a third category, described variously as mestizos. The fourth element consists of descendants of black slaves who arrived to work on coastal plantations in the sixteenth century. Censuses do not record ethnic affiliation, which in any event remains fluid; thus, estimates of the numbers of each group should be taken only as approximations. As of the 1980s, Indians and mestizos represented the bulk of the population, with each group accounting for roughly 40 percent of total population. Whites represented 10 to 15 percent and blacks the remaining 5 percent.