(limˈpjeθa ðe ˈsaŋɡɾe), also known as limpeza de sangue (lĩˈpezɐ ðɨ ˈsɐ̃ɡɨ, limˈpeθɐ ðɪ ˈsaŋɡɪ) or neteja de sang (nəˈtɛʒə ðə ˈsaŋ), literally "cleanliness of blood" and meaning "blood purity", was a racially discriminatory term used in the Spanish and Portuguese Empires during the early modern era to refer to those who were considered to be Old Christians by virtue of not having Muslim or Jewish ancestors. In both empires, the term played a major role in discrimination against suspected crypto-Jews or crypto-Muslims. In Spain's American colonies, it helped define the casta system and was expanded to include those who were not of indigenous or African descent.
By the end of the Reconquista and the conversion or expulsion of Muslim mudéjars and Sephardi Jews, the populations of Portugal and Spain were all nominally Christian. Spain's population of 7 million included up to a million recent converts from Islam and 200,000 converts from Judaism, who were collectively referred to as "New Christians". Converts from Judaism were referred to as conversos and converts from Islam were known as Moriscos. A commonly leveled accusation was that the New Christians were false converts, secretly practicing their former religion as Crypto-Jews or Crypto-Muslims. The concept of purity of blood came to be focused more on ancestry than on personal religion.
The first statute of purity of blood was enacted in Toledo, Spain, 1449, where an anti-converso riot succeeded in gaining a ban on conversos and their descendants from most official positions. Initially, these statutes were condemned by the monarchy and the Church; however, in 1496, Pope Alexander VI approved a purity statute for the Hieronymites.
This stratification meant that the Old Christian commoners might assert a right to honor even if they were not in the nobility. The religious and military orders, guilds and other organizations incorporated in their by-laws clauses demanding proof of cleanliness of blood.