Casta paintings, are defined as the building blocks of difference, it means "lineage, breed or race, to describe as a whole, the mixed-race people which appeared in the post-conquest period" (http://realhistoryww.com/world_history/ancient/Meso_America_Casta_Paintings.htm). This evolved into a frustration, as the Spaniards realized that Mestizos, Mulattos, or Zambos would mix with either, as well as Europeans, and create even more blurred mixes, ones that weren't clear in the social construct. The main concept of the Casta paintings were to group races and sub-races into different categories; there were sharp defining "lines" that stated social status, position, and class.
Going back to the topic of colonization, conquistadors, such as Catalina de Erauso, were the main contributors for the slow, yet steady, control of the indigenous empires. As stated in Catalina's journal, she, and many other Spaniards soldiers, fought repeatedly against the indigenous people in order to claim the land. In the battle of Valdivia, Catalina stated that she had to charge after the Indigenous chief, kills him, and is honoured as a Lieutenant of Alonso Moreno's. To the Spaniards, a battle won is a step closer to the full control of the riches of Latin America. The Spaniards were full of greed, and wanted to establish themselves as superior to the indigenous people that ruled the land before them.