The history of the Jews in the current-day Spanish territory stretches back to Biblical times according to Jewish tradition, but the settlement of organised Jewish communities in the Iberian Peninsula possibly traces back to the times after the destruction of the Second Temple in 70 CE. The earliest archaeological evidence of Hebrew presence in Iberia consists of a 2nd-century gravestone found in Mérida. From the late 6th century onward, following the Visigothic monarchs' conversion from Arianism to the Nicene Creed, conditions for Jews in Iberia considerably worsened.
After the Umayyad conquest of Hispania in the early 8th century, Jews lived under the Dhimmi system and progressively Arabised. Jews of Al-Andalus stood out particularly during the 10th and the 11th centuries, in the caliphal and first taifa periods. Scientific and philological study of the Hebrew Bible began, and secular poetry was written in Hebrew for the first time. After the Almoravid and Almohad invasions, many Jews fled to Northern Africa and the Christian Iberian kingdoms. Targets of antisemitic mob violence, Jews living in the Christian kingdoms faced persecution throughout the 14th century, leading to the 1391 pogroms. As a result of the Alhambra Decree of 1492, the remaining practising Jews in Castile and Aragon were forced to convert to Catholicism (thus becoming 'New Christians' who faced discrimination under the limpieza de sangre system) whereas those who continued to practise Judaism (c. 100,000–200,000) were expelled, creating diaspora communities. Tracing back to a 1924 decree, there have been initiatives to favour the return of Sephardi Jews to Spain by facilitating Spanish citizenship on the basis of demonstrated ancestry.