Feudalism

a legal and administrative order founded upon the exchange of reciprocal undertakings of protection and loyalty among the administrative, military and ecclesiastical elite of Europe and often Japan, and sometimes other societies. Feudal land ownership is commonly contrasted to Allod Ial land ownership (Property Rights)... just as often, feudalism describes a network of social and political agreements that essentially put "public power in private hands," as J R Strayer phrased it.

[To](http://users.ids.net/~marcom/historint/Med Bookrev.html) J R Strayer, it was the political-military structure which made the society and age feudal, thus the attempts to use social and economic factors to define feudalism fall short in that such a template can be applied not just in the Middle Ages, but in many disparate times and places, which would not be of much use in historical analysis.