People began to feel safer in the Middle Ages because___________ and _______________ had stabalized Europe.
Since this is not my area of expertise, I searched Google under the key words "Middle Ages stabilized Europe" to get these possible sources:
http://educationforum.ipbhost.com/lofiversion/index.php/t2506.html
http://vc.ws.edu/engl2410/2002/unit4/01Renaissance.htm
http://www.historicaltextarchive.com/books.php?op=viewbook&bookid=64&cid=51
http://en.wikipedia.org/wiki/Early_Middle_Ages
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In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.
I hope this helps. Thanks for asking.