I was unaware of the Jews ever been sought out or given power in Europe. Do you have a cite for that, sounds interesting.
IIRC, the Jews in Europe where often the source of credit (Christians being forbade to do such by ban on charging interest from the Church) in Europe.
Control of money = power quite often, even if unintentionally.
What Sindawe wrote. I would caution against thinking of Jews (or any ethnic group) as not having an essentially "human" human nature. Humans like power, status, and influence. Such are struggled over and rarely just fall into someone's lap without a great deal of effort on the part of the lap's owner.
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Thomas Sowell gives the best description of what he calls "middlemen minorities" in several of his books. Yeah, that doesn't really narrow it down, given his could-choke-a-goat bibliography:
http://www.tsowell.com/writings.htmlSowell has a series of Q&As on youtube I can not reach from where I sit. Seven or more, IIRC.
WikiculturalmarxistPedia even has an entry:
http://en.wikipedia.org/wiki/Middleman_minoritySowell and many others take a delicate approach, fearing accusations of antisemitism, delving into the economic aspects of mmm without illuminating the implications of economic success, liquid assets, and a culture/ethny alien to the locals. Some of those aspects involve a close association with the local powers, be they feudal lords, satraps, or emperors, the exercise of that power, and the de facto and de jure status that came with all that. MMMs in general and Jews in particular were in such a capacity from the Ottoman Empire (& pre-Ottoman despotic regimes going back to the Persians) west through Europe to the British Isles. Not sure about the nordic areas on the north side of the Baltic.
A summary of how it worked can be read here:
http://en.wikipedia.org/wiki/Court_JewIt has a listing of resources for greater detail. It does get some things wrong, such as the blanket prohibition of Jews from owning land before the enlightenment. True in some times and places, not true in others. (A disinclination on the part of the Jewish subculture for real assets and an affinity for liquid assets is shared by other mmm even where mmm ownership of property is hunky-dory. If there is a history of your sort being given the boot, wealth in a portable format has much going for it...)
Probably the best place to start for a soup-to-nuts history of the Jews is Paul Johnson's A History of the Jews: http://www.amazon.com/A-History-Jews-Paul-Johnson/dp/0060915331Johnson also treads lightly and has only small passages on the political power of Jews in Europe, but it is a fine source for the larger context...which helps the reader keep his head on straight when tackling stickier issues in detail. Johnson is a terrific history writer and the book will keep your attention.
If you google on this topic you are going to find a whole lot of chaff. Some chaff will be tinfoil hatter and/or rather ignorant and irrational antisemitic drek. The other chaff is the odd form of Tourette Syndrome where instead of spouting off into obscenity in nearly every conversation, the author spouts off into accusations of antisemitism. Both sorts of chaff involve much accusation and heat (little data and light) and focus on the weakest/extremest portions of their opponents' positions. The accusations are why Sowell and others are much more forthcoming about non-Jewish mmm. Similar mmm characteristics, but less risk of career suicide when talking about, say, Indians in Africa.
Least controversial place to start would be histories of post-Roman Europe that focus on the dynasty and court of particular potentates. Austria, Spain, Portugal come to mind. Pretty dry stuff, plenty of politics and such and usually written by academics not interested in a good read. (The Abravanel family in Spain & Portugal are an interesting study in the entry, rise, and expulsion.)
Another resource are triumphalist histories of Jews written by Jews. Similar to some of the triumphalist literature written about America, the Irish, etc. Extended and more or less academic renditions of "America, Eff Yeah!," "How the Irish Saved Civilization," and the like. Such histories of Jews written by non-Jews are usually met with praise. Things get prickly (for Jewish and non-Jewish writers) if the author then goes to case studies and things get really ugly if the author then tries to generalize. (Jewish writers who go too far off the reservation get slapped about, too.) I can provide some examples of professional seppuku following this pattern.
HTH. It is an interesting topic, one best approached from a broad perspective and then narrowing down. Start with Paul Johnson and then work your way into it would be my suggestion.