Jews came to the Iberian Peninsula during the reign of the Roman Empire, much earlier than the kingdom of Portugal was created. Some of them might had to migrate due to the destruction of the First Temple in Jerusalem or later when the Second temple was destroyed, but these facts are not sure. Others came from the northern Africa. Between the V and the VIII century Visigoths ruled and did not allow to practice Judaism. In 711 CE came the Moors, the Muslims, but they were quite tolerant at that time and Jews could practice their faith and live in Portugal as long as they payed taxes, same as Christians. They no longer had to hide their faith and were allowed to work as doctors, craftsman, poets, writers, philosophers and scientists. This golden period lasted until 1036 when the Cordoba caliphate finished.
After the Reconquista the first Portuguese kings trusted rabbis as they tax/financial specialists. Synagogues were built, the communities grew. Unfortunately the catholic clergy began to create tensions. In 1478 the Inquisition began in Spain. In 1492 the Spanish rulers Isabel and Fernando expelled Jews from the country. Only those who converted to Christianity could stay. Those who secretly continued their religious practice were called marranos. More than 90 thousand seeked shelter in Portugal, but just four years later a royal law would give one choice: convert or leave the country. Children were taken away from their parents and baptized. One of the darkest moments was April 1506, the so called Lisbon massacre or the Easter Slaughter. Thousands of Jews were attacked, accused of being heretics, hundreds were killed and burned at a stake.