I don't think Feudalism was unique in the middle ages or in Europe. Feudal-like societies existed from the 3rd millenia BC in many places and there is good reason (and few evidence) to believe that some form of feudalism was the one of the primal social and political organizations used by humans.

Usually in history similar conditions produce similar results. Never identical, because the variables when talking about human societies, are countless. But similar, nevertheless.

The Medieval Fedualism is practically the adoption of the tribal hierarchy to the declining roman world, with defining parameters the absence of a strong central authority, the lack of literacy, security and organization - an odd hybrid, really. But there was nothing unique in it, except - perhaps - the form and etiquette (feudal contracts, obligations etc. etc.)

It was present as a social organization and we have sort-of-serfs (peasants considered part of the property-land) in previous societies as well.

I read that the development of the saddle played an important role in the emergence of feuldalism. Horsemen would defend villagers from bandits and brigands and in exchange the villagers would give them a form of protection money.

As the leading barbarian succesor states in the area grew and conquered the lesser states the horsemen or knights would keep their land but owe homage to the conquering king. This would save the conquerors having to supply costly garrisons.

This basic system refined over time and the obligations became more concrete. But the role of the knight protecting his peasants eventual became true officially only.

well I give it a shot to address your questions more fully.

starting with organized crime. Useing the definition of Fuedalisium supplied by wikipe http://en.wikipedia.org/wiki/Feudal - http://en.wikipedia.org/wiki/Feudal  it is not an exact match in the case of the protection rackets run in those circles. As the lords of organised crime do not own the property that they are suppling protection to. If you look at organised crime more broadly it does have some distinct fudeal elements. the head of a "family" owing certan things to those under his camand and visea versa. Particullarly if you believe that the "Sapranos" is an accurate depiction of the situation.

There is several exaples of feudalisum Here http://en.wikipedia.org/wiki/Feudalism_%28examples%29 - http://en.wikipedia.org/wiki/Feudalism_%28examples%29

Conditions for feudalisum are harder. An agrocultural based ecomomy working mostly on barder rather than cash, a need for protection, social status conected to land ownership, lack of strong centralized government with a standing professional army, things like that. 

as to a reason to study it I think on that more.

well I give it a shot to address your questions more fully.

starting with organized crime. Useing the definition of Fuedalisium supplied by wikipe http://en.wikipedia.org/wiki/Feudal - http://en.wikipedia.org/wiki/Feudal  it is not an exact match in the case of the protection rackets run in those circles. As the lords of organised crime do not own the property that they are suppling protection to. If you look at organised crime more broadly it does have some distinct fudeal elements. the head of a "family" owing certan things to those under his camand and visea versa. Particullarly if you believe that the "Sapranos" is an accurate depiction of the situation.

There is several exaples of feudalisum Here http://en.wikipedia.org/wiki/Feudalism_%28examples%29 - http://en.wikipedia.org/wiki/Feudalism_%28examples%29

Conditions for feudalisum are harder. An agrocultural based ecomomy working mostly on barder rather than cash, a need for protection, social status conected to land ownership, lack of strong centralized government with a standing professional army, things like that. 

as to a reason to study it I think on that more