You could look at the wikipedia entry about the history of antisemitism. This is getting quite historical, but:
- About 2,000 years ago, the Roman emperor Hadrian scattered Jews from the lands of Israel into diaspora. There were Jewish minorities all over the former Roman empire, and later all over the world.
- Many Jews retained their religious identity, which made them retain their ethnic identity. (Or rather identities. There were worlds between a shtetl in eastern Europe and a Sephardic congregation in Spain. The groups diverged.)
- Europe in the middle ages was not exactly a tolerant place, yet many Jews still retained their religion.
- In many places, Jews were excluded from significant land ownership or guild membership. Before the industrialization, this left them trade and banking.
That means a couple of centuries ago, Jews were suitable for being scapegoated in many places. They were regarded as other than the mainstream religion of the place (and remember how Protestants and Catholics massacred each other about much smaller differences). They were a common target for pogroms and looting. Later, they were a common target for conspiracy theories because of the influence and secrecy ascribed to bankers.
Over the 19th century, they were slowly becoming part of mainstream society -- going to the same schools, working in the same jobs, and so on. But time and again agitators targeted them. There was a small movement aimed at getting back into Palestine, which was under British control after WWI. Then Nazis took power in Germany and murdered millions of Jews in Europe.
After WWII, larger numbers of Jews moved into Palestine. This caused conflicts with the population which had lived there for centuries, and who were not willing to accept 2,000-year-old claims at face value. There was a kind of civil war which left UN-negotiated borders that satisfied nobody. Several times the Arabs attacked to get the land back, several times the Israelis won and expanded their territory even more. (They gave some back in negotiations, while expanding settlements elsewhere.)
So there are different kinds of antisemitism:
- Christians who accuse them of being weak and being merchants and bankers who profit from other peoples' work. That was the Nazi propaganda.
- Muslims who accuse them of being strong and being conquerors.
Note my use of Israeli for citizens of Israel after the foundation of Israel. Mixing the two up and blaming the local Jewish diaspora for complaints about the Israeli government is typical of much modern antisemitism.