I haven't written a Civilization IV post for quite awhile, but I haven't given up on them. Given all that's happened in the last week, I think I need to get back to basics, as it were, and write a substance heavy post.
Feudalism was first incorporated by the Chinese, probably during the time that Rome was still a kingdom - so, at least 2500 years ago. It arose as a means of controlling wide-ranging territories; a Warlord had hardly any local power, and by investing nobles with local power the Warlord had the benefit of having his borders defended, and having the privilege of drawing up an army from among the nobles in times of trial. However, it became evident that these "Governors" possessed a great deal of power, enough to impose their will upon any central authority.
Following the unification of China in the 4th century B.C., the first emperor of the so-called Qin (or Ch'in) Dynasty, Shi Huang, attempted to break the power of the nobles by abandoning feudalism in favor of a strong central bureaucracy. While eventually this idea would have merit in later centuries, Huang's success with it was questionable. Throughout his reign, would-be governors continued to chafe in favor of being granted fiefs, while assassination attempts to rid China of Huang in favor of a more 'feudal-friendly' emperor were made. Part of Huang's response was to attempt a destruction of all previous Chinese history - he ordered the burning of many books, and the burial of many scholars, often while they were alive.
In the end the Governors won. With the death of Huang, China reverted to a feudal society. For much of its history afterwards, emperors were at the mercy of their governors. The central authority was eventually established to a greater degree during the Tang Dynasty (in the late 7th/early 8th century), which brought some stability to the ruling family ... the edges of empire were always at the mercy of independent warlords, however, who often sided with enemies against the center, and often fought one another for greater territory.
The rise of feudalism in Europe is better known to the western reader, and is usually described as a series of agreements between King and Nobility, or between the noble lords and the workers of the noble's land. Labor was the primary substitute of exchange; a peasant was allowed such-and-such an amount of time to work land which was granted for their use (not their ownership) in exchange for working upon the Lord's manor - tilling fields, herding animals, cutting wood, providing fish, mending the Lord's buildings and so on. Certain members of the Lord's household became permanent workers in the manor, producing the needed amount of candles, prepared foods, clothing, luxuries and so on, in exchange for a more comfortable lodging than the peasant could count upon and better eating than the peasant could expect. Other persons within the Manor were specialty workers, such as the miller who maintained and ran the mill that ground wheat into flour, or the mason or the carpenter, along with the steward of the Lord's house, the reeve who managed the Lord's stock and herds, or the hayward who managed the work of the men in the Lord's fields.
The population of a manor could range anywhere from a few dozen to as many as eight hundred; and the work was shared and delegated without the use of any unit of exchange beyond food. For the most part, in the Dark Age of the 6th and 7th century, this work was done to produce a self-sufficient economy ... food was not shipped to town to be sold, because there were no 'towns' as we understand them in most parts of Europe, and there was no money.
The disappearance of money from Europe occurred due to a number of factors; the Romans had, for century after century following the rise of Empire, devalued the currency in order to continue to provide money for their unsustainable infrastructure. By the fourth century the Empire was heavy with inflation, stagnant economies and soldiers that were constantly finding themselves without pay - and therefore turning on the state itself in a series of usurpations that only served to further weaken the empire. The scourge of barbarians that tore through central Europe - Huns, Vandals, Goths, Saxons, Franks, Avars, Slavs and so on served to collect the plunder that could be found into very few piles (so that money fell out of circulation), aided by the desperate attempts of local governments to pay these groups tribute in order to these same groups to keep themselves from getting killed. By the end of the 7th century, with much of the existing wealth being funneled into the coffers of Byzantium or the successful Arab conquests in North Africa, coin became rare indeed. Many of the existing, known mines of central Europe had been heavily worked by the Romans up until their demise, so that the production of new metals dropped off. Foreign metals, that might have come from China or India, were diverted into the growing economies of East Africa or Southeast Asia, and away from Europe.
The arrangement of social hierarchy within the feudal manor provided a stability which could not be achieved with a more traditional economy. However, with the unification of Central Europe under Charlemagne, and that state suddenly rich with metals obtained through arrangements with "foreign" markets in Western Spain and along the Adriatic, town-building became the rage in the Elbe and Rhine valleys throughout the 9th century. Even as these were plundered repeatedly by Vikings through the next few centuries, who struck as far away as Sicily or the heart of the new Russia - Volhynia, Kiev and Vladimir - the development of trading towns continued. As early as the 11th century, nobles were losing their grip on the peasantry, who were fleeing to towns in exchange for wages and relative personal freedom.
Europeans had similar experiences with Feudalism as the Chinese - groups of nobles were able to unite against this throne or that, establishing more and more independent states who were given greater and greater autonomy inside the 'Empire.' Both Italy and Germany became hopelessly fragmented; Spain as well, though to a lesser degree, following the wars against the resident Berber's there. The twin kingdoms of Lithuania and Poland both swelled into huge states comprised mostly of independent nobles with a very weak central authority - as was made very evident with the arrival of the Mongols in the 1230s. For two centuries thereafter, while the Russians, Poles and Kievans had nominal authority in their kingdoms, heavy tributes were paid regularly to their Mongol overlords. But at this point I am digressing.
The return of capital to Europe made the feudal system impractical. Lords began substituting taxes for the previously expected labor, and peasants began to shuttle their goods into towns to obtain the money to pay these taxes. Central authority shifted from the manors - where military power had previously reigned - to the towns, who could afford to pay richly for mercenaries in times of trouble. The dominance over the manors continued apace through the next two centuries - stymied somewhat by the Black Plague, which hit the towns heavily - until the development of the cannon made castles useless in times of war. By this time - late 1300s - Europe had slid firmly into a mercantilist economy, with towns being the political centers of life.
Without wishing to beat the point home, it was this reason why Russia proved so much stronger than its neighbors Kiev, Poland and Novgorod; from the beginning Russia was built from strong urban centers, promoting a central authority, while Russia's immediate enemies continued to be sprawled in predominantly rural societies. Poland's condition as this was notorious - over the ensuing centuries, its neighbors would gobble Poland up, bit by bit.
Turning then to D&D, it must be noted that the dependence on coin in the game clearly indicates that D&D is not - as it is often described - based upon a feudal/Medieval society. The changeover from manor to town that I describe above happened much earlier in certain parts of northern Europe - the Low Countries or Bohemia - and in Italy long before the 14th century. Wherever money was common enough to be turned over in amounts equally hundreds of coins, nobles of every kind had removed themselves from their estates into the local towns. D&D, as it is described in the books, fits more nearly the sense of early Renaissance than it does a Medieval culture.
If, however, one were to run a true Medieval environment, the characters would have to be considered outside the standard social structure, if they were to have any freedom of action at all. They could hardly drift from manor to manor as easily as they could from town to town ... the arrival of strangers was considered a bad omen, the expectation that they would bring disease, disruption or discontent, along with the dangers that there were there to steal food. Thus, the moment a group of characters arrived in a manor village - with the exception of the one in which they were born - there is a real danger the inhabitants would immediately take steps to kill them.
Food would be the largest difficulty, since it could not be purchased in a town (there were no markets), and needed to be grown. A party would have to choose an area of relative wilderness in order to establish their own food production, and would afterwards have to defend that area against other starving persons - particularly criminal or religious outcasts who were not accepted in society. Everything they wanted to have would have to be constructed with their own hands - if they did not have the knowledge of making swords, they would have to make do with wooden weapons, clubs, spears and so on that virtually anyone can make to some degree. Time would have to be dedicated to herding their own animals, if they wanted a healthy diet, along with picking fruit, cutting wood for the winter and for cooking, mending their homes following storms, exterminating vermin and so on. It would be a hard, unforgiving life ... and the worst of it would be, if they truly built something noteworthy, they'd have no right to stop a noble from taking it, since the party could not 'own' the land they were building upon. Ownership was something that was accorded only through an agreement with the local authorities, and the party would never have been offered that agreement prior to building. Even if the party went to war, and served well, they might still be discounted as being important in the greater scheme of things, since that was the culture of the time. Robin Hood, if the gentle reader will remember, was a Lord before he became an outlaw. He was reinstated to his lands ... his outlaw friends were not given lands of their own.
I think it could be done, but it would require a very different thinking process for players to find any fun in it. For myself, I like culture - which is why I run a late Renaissance campaign. But to each themselves.