In the 8th Century BCE, Babylonian Jews were exiled from Babylon when their land was taken over. Again they were treated as a defeated enemy and not targeted because of their ethnic group.
In the 2nd Century BCE, Jews were made to conform to Grecian ideals as the Greeks forced their culture and practises on the Jews. They even had the temple in Jerusalem dedicated to Zeus. Like the Nazi oppression, Jews were resented because of their state of economic prosperity.
The Romans also oppressed the Jews as they used violence and brutally quashed Jewish revolts. This wasn’t very similar to the Holocaust because the German Jews had made an effort to fit into German society prior to the Nazi regime. However, although the scale was different, Jews were treated in a similar hostile manner and faced violence and threats.
Although there was no plan to systematically wipe out the Jews, all these ancient civilisations, the bases on which modern civilisation is built, all persecuted Jews; the motives were more religious and security based rather than ethnic discrimination.
Anti-Semitism was found in the early Christian gospels because of the part the Jews played in Jesus’ death. They were demonised just as the Nazis demonised them in modern times.
The Crusades were the culmination of years of anti-Semitic teachings in early Christianity. Jews were forced to mark themselves, they were exiled and they were brutally attacked. In the time leading to the Holocaust similar things happened.
Throughout the 16th Century CE Jews were exiled from countries such as Italy, Austria and Spain if they didn’t convert to Christianity. This bears a similarity to the Nazi policy when Jews were stripped of their citizenship and forced out.
The Russians in the 19th Century organised racially motivated attacks on the Jewish communities in Russia. The Jews were forced to live in restricted areas. They had been blamed for the assassination of the tsar and the new one established his authority by organising terror attacks on the Jews. Jews were also thought to be a nuisance to society, their money lending and vodka shops were leading the peasants astray. The racial rather than religious motives behind the persecution made the Russians very similar to the Nazis however, their attacks were very sporadic and unruly. Hitler used more ordered lynch mobs or his SA to terrorise the Jews.
All of these events bore certain similarities with the Holocaust and that is why I don’t think the Holocaust was unique in Jewish experience.