You probably know about the widespread mistreatment of Jews in Spain, even if your first thought when someone says “Spanish Inquisition” is a Monty Python sketch. But Spanish and Portuguese antisemitism isn’t just a historical artifact. According to historians like David Brion Davis, the Spanish categorization and treatment of Jews “provided the final seedbed for Christian Negrophobic racism,” and “gave rise to a more general concern over ‘purity of blood’—limpieza de sangre in Spanish—and thus to an early conception of biological race.”
The discrimination against Spanish Jews peaked decades earlier, in 1391, when a fanatical priest incited anti-Jewish mobs with the slogan “convert or die.” A third to a half of the Spanish Jews—the largest community in Europe at the time—were converted to Christianity, the greatest mass conversion in modern Jewish history. [...]
The most important of these conflicts took place in Toledo, and began as a tax revolt. On January 25, 1449, Alvaro de Luna, a favorite of King Juan II, demanded from Toledo a loan of one million maravedis. The townspeople actively resisted payment, and a mob quickly obtained control of the city gates. [...]
On June 5, 1449, Sarmiento issued the Sentencia-Estatuto, the first set of racial exclusion laws in modern history. It barred conversos, regardless of whether they were sincere Christians, from holding private or public office or receiving land from the church benefices unless they could prove four generations of Christian affiliation. [...]
The crime of which those of Jewish lineage were guilty was deicide. The alleged Jewish role in killing Christ was a kind of original sin, inherited by Jews and passed down in the blood. Because the act superseded the rite of baptism, baptism could not purge conversos of this crime. [...]
Along with slavery, Spain exported limpieza. In 1552, the Spanish Crown decreed that emigrants to America must furnish proof of limpieza. The Spanish deployed limpieza throughout Spanish America and the Portuguese adopted it in Brazil. In its new environment, limpieza began to mutate, beginning to refer to an absence of black blood as well as an absence of Jewish blood.