The countries of the European Union are currently facing a large wave of immigrants and refugees. Historically speaking, do we have examples or proof of such streams of refugees affecting their area of destination positively or negatively?

Sorry, we don't allow throughout history questions. These tend to produce threads which are collections of trivia, not the in-depth discussions about a particular topic we're looking for. If you have a specific question about a historical event or period or person, please feel free to re-compose your question and submit it again. Alternatively, questions of this type can be directed to more appropriate subreddits, such as /r/history or /r/askhistory.