There have been many anti-semitic killings throughout history, the holocaust was by no means the first example of this. Here are just a few examples:

The Romans persecuted Jews on a number of occasions, most famously after the Jews revolted in 66CE, which resulted in the destruction of the Second Temple in 70CE. They revolted again in 132-136CE, and suffered huge casualties as a result. Cassius Dio estimated that c.580,000 Jews died in the battles and sieges against the Roman forces.

Another famous example of targeted Jewish killings happened in York, England in 1190CE. This was the time of the Crusades, and there was a lot of hatred throughout Europe to non-Christian religions. On March 16th, these feelings culminated in the massacre of 150 Jews in York, which was the entire Jewish population at the time.

Martin Luther was famously anti-semetic, in his work "On the Jews and Their Lies, he writes, '(they are) full of the devil's feces ... which they wallow in like swine,'. He encouraged a 7 point series of violent attacks on Jews to ensure their demise which included the burning of synagogues and the removal of their wealth.

Whilst no rulers enacted all of Luther's reforms, a few laws were enacted such as when Jews were banned from Brandenburg-Küstrin in 1572. In 1614, a Calvinist preacher called Vincent Fettmilch reprinted Luther's work in an attempt to create anti-Jewish fervour, and in Frankfurt anti-Jewish riots saw the death of 3,000 Jews and the expulsion of the rest.

In the Muslim world, rulers could be just as anti-Semitic as in the Christian world. In Granada (Southern Spain) in 1066, the local Muslim populace assassinated the Jewish vizier, and then massacred 4,000 of the Jewish population. A poem written the same year by Abu Ishaq contains the line, "Do not consider it a breach of faith to kill them, the breach of faith would be to let them carry on." In which we can see the Anti-semetic ideas, and justification of actions against them.

However it must be said, that generally in the pre-Modern Islamic world the Jewish population was tolerated much more than in the Christian world.