This article is from the Tolkien Newsgroups FAQ, by Steuard Jensen sbjensen@midway.uchicago.edu with numerous contributions by others.
Tolkien's works draw from quite a few periods of human history, and
many aspects of Middle-earth distinctly resemble their real-world
counterparts in the Middle-ages. However, there are substantial
discrepancies in society and culture that indicate that other periods
in history also made large contributions (as one example, in Letter
#211 Tolkien compared several significant aspects of the society of
Gondor to that of ancient Egypt). The relative influence of Medieval
and other periods has been hotly contested.
 
Continue to: