Anti-Semitism has its roots in ancient times, with some of the earliest recorded instances of anti-Jewish sentiment appearing in the writings of the ancient Greeks and Romans. It has been argued that anti-Semitism was a response to the success of the Jewish people in the ancient world, as well as to their religious beliefs and practices. In the Middle Ages, anti-Semitism was further fueled by religious and political factors, such as the Crusades and the Inquisition. In the modern era, anti-Semitism has been linked to the rise of nationalism and the emergence of racial theories.