Throughout history, many rulers, empires and nations have oppressed their Jewish populations or sought to eliminate them entirely. Methods employed ranged from expulsion to outright genocide; within nations, often the threat of these extreme methods was sufficient to silence dissent. The history of antisemitism includes the First Crusade which resulted in the massacre of Jews; the Spanish Inquisition (led by Tomás de Torquemada) and the Portuguese Inquisition, with their persecution and autos-da-fé against the New Christians and Marrano Jews; the Bohdan Chmielnicki Cossack massacres in Ukraine; the Pogroms backed by the Russian Tsars; as well as expulsions from Spain, Portugal, England, France, Germany, and other countries in which the Jews had settled. According to a 2008 study published in the American Journal of Human Genetics, 19.8% of the modern Iberian population has Sephardic Jewish ancestry, indicating that the number of conversos may have been much higher than originally thought.

What was one method used to entirely eliminate Jewish populations?