Didn't the Crusaders do this on the way to the Holy Land. or was that just the peasants crusade and Peter the Hermit?
Holocaust level? I'd say impossible before late 19th century simply because there was no bureaucratic base and actual capacity to ship so many people in camps and kill them with such speed. (that's ignoring the fact that there was no Nazi equivalent who'd want to exterminate Jews as oppose to convert or expell them). Which is why pogroms ould never reach Holocaust levels, there simply was no capability to mold such violence on large, nation wide scale
Now, if you are talking about genocide in terms of removing the presence you had cases of countries giving Jews a choice of conversion or expulsion. But that's not genocide, it's ethnic cleansing and forced assimilation.
Did the prejudice have its roots in Roman times where Judea was a hotbed of rebellion and stubborn Judaism or did the prejudices begin to manifest after the fall of the Roman Empire? OR did the Antisemitism start going after the Christianization of the Roman Empire?
It began when Judaism officially divorced Christianity from itself, leaving a bias against Judaism in Christian ideology which then carried on into governmental practice when it was formally adopted by the Roman Empire. Antisemitic laws then created by Rome such as edicts preventing Jews from serving in office, associating in public with Christians, etc, carried antisemitism into populations throughout the Roman Empire.
Was that abnormal for the place and time though? According to the bible the ancient Hebrews did that to the Canaanites. Later the Mongols would slaughter entire civilizations.That was Babylonian captivity, they are arguably much more "civilized" than the utterly Brutal and bloodthirsty Assyrians. Assyrians, who deem slaughtering entire male population of a nation and raping and enslaving their women as a standard method to subjungate a rival kingdom...
Was that abnormal for the place and time though? According to the bible the ancient Hebrews did that to the Canaanites. Later the Mongols would slaughter entire civilizations.
So 'civilization' then was dependent on being pragmatic enough to keep around forced labor?The whole scale slaughter of populations was always expectional it usually didn't make sense to kill all those potential workers.
So 'civilization' then was dependent on being pragmatic enough to keep around forced labor?
I'm pretty sure it was the other way around. Jesus was executed by the Romans for sedition, as was standard at the time. Later, Paul was gathering converts for the Jesus movement without requiring the non-Jewish males to be circumcised. When the authorities in Jerusalem put their foot down about this and demanded that they be circumcised, which would doubtless mean that almost all of them would refuse (adult circumcision at the time being horribly dangerous with a high fatality rate)
"State sanctioned Pogroms" weren't a part of historical state policy before the 19th century, unless you count the Spanish Inquisition.
Kielce pogrom
The Kielce Pogrom was an outbreak of violence against the Jewish community centre' gathering of refugees in the city of Kielce, Poland on 4 July 1946 in the presence of the Polish Communist armed forces (LWP, KBW) which resulted in the killing of 42 Jews. Polish Communist courts later tried and condemned nine people to death in connection with the incident. Numerous academic sources assert that the massacre was instigated by the Soviet-backed Communist security corps, possibly for propaganda purposes, attempting to discredit Poland's anti-Communist stance and to maintain totalitarian control over the country.
Because the top-secret case files were destroyed, the academic inquiry is ongoing with regard to possible secret coordination with the NKVD by the Polish authorities.[1][3] In 2001–04 the Institute of National Remembrance (IPN) conducted an investigation into the pogrom and closed the case stating (without entering into details) that the events of 4 July 1946 were a result of a mishap. Another communiqué published by the IPN two years later confirmed only that four decades after the fact the remaining paper trail was still being destroyed by the pro-Soviet security police under Gen. Czesław Kiszczak.
As the deadliest pogrom against Polish Jews after the Second World War, the incident was a significant point in the post-war history of Jews in Poland. It took place only a year after the end of the Second World War and the Holocaust, shocking Jews in Poland, many Poles, and the international community. It has been considered a catalyst for the flight from Poland of most remaining Polish Jews who had survived the Holocaust.
http://en.wikipedia.org/wiki/Kielce_pogrom
There are way too many instances of "Jewish extermination" in history to even begin to put them here. Many countries simply expelled the Jews (England in the 13th century is one), some used a combination of expulsion and conversion or death (Spain/Portugal), and "local" massacres that killed most if not of all of the Jews in a given area (and any survivors tended to leave) and so forth. When the Jews were concentrated in Israel in ancient times you could have a combination extermination/conversion wiping out the religion. Once Jews began to spread out (during the Roman Empire for sure even before the destruction of the Temple/revolt) its hard to get a total wipeout, or even reduction of numbers so low they fade away.
When you get to the 20th century you have railroads and the industrial capability to wipe out all the Jews in an area "you" control, but unless you/your ideology controls the world you won't get them all.
As to why the Jews were persecuted, they were only seriously persecuted as a religion rather than as a social/political group after the advent of Christianity. Likewise in Islam. The basic reason for this was that both Christianity and Islam, building on concepts from Judaism but seeing themselves as the new or replacement prophecy and came down on the Jews as rejecting the new revelation. Specific charges about the "blood libel", spreading plague, etc simply built on this basic issue.
FWIW one of the reasons Jews tended to be bankers/moneylenders in Christian Europe was this was forbidden to Christians, and many professions were closed to Jews (via guild rules, nit allowed to own land, etc). Furthermore the rate of literacy amongst Jews was much, much higher than that in the lay Christian population - a requirement for letters of credit etc. Not only did this cause resentment (nobody likes the guy who forecloses or holds a loan) but expulsion, persecution was a great way to wipe out debts.