The protocols of Zion is an anti-Semitic booklet published in The USSR in the end of the 19th century.
The origin and the true colours of the booklet are unknown ,but the things we know is that it was written by a secret agent of the KGB in is room, alone. It was written in the goal to calm down the Russians against the czar.
In the protocols it was said that the Jewish people were planning to take control of the world by taking hold of global institutions and turning non-Jews into slave. It was a group of 24 powerful Jewish that planned to control other countries and to be king of the world. The group, called the Zions, were secret and appart of the world.
People then started reading the pamphlet, even if it was restricted, and started blaming Jewish for all their curse. The population believed that all the Jewish were bad and were attempting to rule the world. They tough that they were all part of the Zions and that’s why they were starting to exclude them of the society.
Of course it was a conspiracy theory but some people didn’t tough this way. The beginning of WW2 was because the Germans thought that the Jewish were the cause of their poor economy. They than started to exterminate them to put the economy back to normal.
Even some people still believe this way, there are several groups and they manifest to blame the Jewish and to try to exterminate them again. Not everyone is like this but just to know that there is still people that believe like this nowadays.