The Khazaria hypothesis confuses two events and the real "Hebrew" Jews with a small number of Judaized Turkic Khazars ( who must be considered Jewish by Jewish law, just like A Turk who becomes a German citizen must be considered German by German law). But the devil is in the details.
Here's what happened:
Event # 1. Some 3500 years ago, a group of Mesopotamian Semitic tribes ( similar to Arabs) created a new monotheistic religion about God being one ( Ahad), a person following this religion would be called Yahud ( one with God). They proselityzed for a while ,but then stopped, and only mingled and married among themselves.
The other name for this group was Isra-el ( those wrestling with God) . Because most such people belonged to various Semitic ethnicities of the Middle East and then, they converted other neighboring ethnicities, the eventually jelled into a Semitic supra-ethnicity with its own religion.
When they moved to other places, people called them
Habiri ( Hebrew) which means "one from beyond Euphrates" ( in modern day Iraq). They established Kingdoms of Judea and Israel in what is known in Greek as Palestine ( after killing its inhabitants) and lived there for several hundred years. The Jews are called the Hebrew Nation by many Europeans, also.
They were conquered by Romans and then, after several uprisings against the Roman rule, a Roman emperor had most of them deported and scattered around the Roman Empire. The bulk of these settled around the Rhine area where they lived as a state within a state. Others went to Spain, etc.
Did they form a distinct race? From the point of view of Europeans, yes! Because people who practiced this religion were basically of Semitic appearance/race. Germans called them Semites and those people who hated them were called Anti-Semites. In Romanian, Italian and Russian, the word for a Jew is
evreu,
ebreo and
yevrey, respectively. Again, "one from beyond the Euphrates". They lived in Central Europe, in their majority, and in other neighboring countries. They were not accepted because of the Semitic origin ( their faces were different- they were seen as non Europeans, as Middle Easterners) and a different religion.
Hence, in most countries, they lived as non-citizens, no matter how many generations there, Jews rarely intermarried,and the addition of European blood was very rare, too. They lived in areas called ghettos with their own government-in-exile called the
Kahal. And unlike in America ( North and South) where a birth in the country makes you one of them, in Europe ( and in Asia) only bloodlines can make you one of them.
German kings tried to integrate ( integrate, mind you-- not assimilate) the Jews by giving them last names ( the Jews didn't have last names). So, they gave them pseudo-Germanic-sounding names such as Goldberg, Steinberg, Gladstein, etc. which were not German-sounding to the Germans, and were really mocking names coined artificially. However, to other people, they sounded Germanic. The Russian authorities also gave those Jews who didn't have last names funny names ending in ski, ich/itz, etc. Horowitz, Berezovsky, etc. To foreigners, these sounded " Russian" but not to the Slavs. The Jews also developed a patois called
Yiddisch which was German mixed with Hebrew. The common name for all these Jews who had settled on the Rhine and who had names like "Abraham Goldberg" was "Ashkenazis- meaning from/living in Germany".
No matter the above efforts to integrate them, many Europeans wanted them out and sent back to the Middle East. They often killed them and persecuted them until a movement was started to finally go back to the Middle East. This movement was similar to the "Back-to-Africa Movement" by American blacks.
When the Jews arrived back into the Middle East, the Arabs living there were aghast- "Who the f*** are you?" Because you see, to Arabs, Jews do not form a distinct race nor a distinct nation. They are Semites just like Arabs. But not Semitic enough. Looking from the Arab eyes, these were
Khawaja, - Europeans. In the Arab society and culture, they only care about these things: 1) language- if you speak Arabic, you're an Arab ( and many Jews spoke Arabic) 2) citizenship - if you are a citizen of an Arab country, you're an Arab 3) religion. This is how Arabs within their societies identify people. Thus, to an Arab mindset, these were only a religion group, not a nation or race. This is very different from the way Europeans identify people. Or Americans - "Where were you born? Where 're you from?"
Hence, the Arabs started telling them to go back to Europe. They were pointing to the quasi- European appearance of many of them ( which happened because of rapes) and European clothes/ behavior. Thus, all hell broke loose.
Incidentally, something similar happened in Africa when American blacks went there. From what I understand, when these Africans saw all these English-speaking people with names such as Leroy Washington and Juanita Williamson arrive at their shore in what would become Liberia, they sure didn't see them as "fellow Africans". They also paid attention to how mixed with whites these were, and many would be seen as pretty much "white people" (looking from the African eyes) by them. So, there you have it-- stuck in between-- in America, you have racist rednecks yelling "Go back to Africa!" and then, in Africa, you have native black Africans, I imagine, yelling at them to "Go back to America!"
They started fighting. The American blacks then conquered them and turned them into plantation slaves.
The Jews also started conquering the Arabs. From the Arab perspective, this was a continuation of the European colonization, and these Zionists were ' Europeans'. So, on the one hand, you have Russians, Poles, Germans, Romanians, Hungarians etc., yelling at Jews to "go back to Palestine", and on the other hand, you have Arabs yelling at them "to go back to Europe".
This is a simplistic picture, but generally this is what happened.Other Jews ended up in other countries and they have different histories but the majority did become what is known as Ashkenazis.
Event #2. Not all Jews ended up in the central Roman Empire. There were some who were living in other areas. Some became teachers of Khazars.
There was a Turkic Kingdom located in the area of Azerbaijan called Khazaria with the capital of Tmutarakan'. A king wanted his kingdom to have a religion and invited mullahs, Hebrew rabbis ( who were possibly living in the Byzantium) and Christian priests, and finally decided that Judaism was the best for him. So, the top echelons of his Kingdom did convert to Judaism and became " naturalized" Jews. However, to the people around them- Slavs in particular- these were still Khazars. They called them Khazars, they fought them as Khazars and they knew that these were not Hebrews. Princes of Kiev have chronicles of them waging wars against the Khazars. Eventually, the adopted religion of Judaism did not help them and their lands were crushed. The Kingdom ceased to exist. It was a fling, basically which was not very successful. Whether these Khazars intermarry with Ashkenazis is still open to debate. Numbers are not really known. Their culture also pretty much disappeared.
The converted Turkic Khazars were thus a very small part of international Jewry, and there were few to none among the Zionist leadership or on the streets of Warsaw, Berlin, Budapest, etc. People like Waitzman, Hertzl, were mainly Ashkenazis and Yiddish-speaking. These are the ones you see on the streets of Williamsburg, NY, the Bronx, etc.
Now, the Khazar hypothesis states that
most E. European Jews are, in fact, of Turkic origin and
are Khazars; not Hebrews. That, in fact, possibly
none of them are Hebrews. Let's assume they are right and these are really a Turkic people. This theory has a few holes:
1) When was the great migration of hundreds of thousands ( or possibly millions) of these Khazars into Germany from the area of Azerbaijan and southern Ukraine? How were they given Germanic sounding names? How did they developed a patois called Yiddisch which was German mixed with Hebrew and which does not have any Turkic words?
The Jews in Hungary, Poland, Romania, etc virtually all spoke that language and all had names such as Greenstein, Rosenstein, etc- clearly names created in Germany and after which, they settled in other, surrounding countries. So, it means that these Khazars migrated into Europe from Azerbaijan and ended up on the Rhine? When was that? Such a huge migration should have been recorded somewhere. However, Germans and other Europeans do not mention it. They all talk about Semites. There is no mention of this enormous movement of people from Khazaria.
2) Why did the European governments and its people call the Jew in Europe " Hebrews", "Semites" and "Judeans for two millenia? Why did they not call them Khazars? Kievans and Germans really know the difference between a Turkic person and a Semitic person. Even the Nazis knew that. Hitler ( initially) wanted to deport all Jews to Palestine, too. He did not want to deport them to Azerbaijan.
3) Finally, the government of Azerbaijan as well as Southern Ukrainian provinces of Donetsk and Zaporizzha do not ever talk about it or acknowledge these. And they differentiate ( in their history) the Khazars from the Jews.
Conclusion: Just like there are fringes in every ethnic group, so these Khazars were a small naturalized Jewish fringe. They are not the Jews you meet in Encino and/or the Bronx.
do assume Ashkhenazis have some Hebraic blood but it can't be a majority. When you move around, mixing happens.
Mixing happens if you have sex. Not if you just "move around'. Jews in Eastern/Central Europe were very isolated from the local peoples and almost never mingled with them. Some mixing took place through rapes, and an extremely rare intermarriage, but physically, they still look Semitic to pure Euro eyes particularly to people such as Poles. Just like mulattoes still look black to white Southerners. It really depends on who does the classifying. In those European countries, a half Jew is still a Jew, just like in the US, a half black is still black.