i think i can add a few more points to the list of things not directly considered yet in this thread.
i shall bare a bit of geek and refer to a loudly touted but poorly executed example: the prime directive. for the non-trekkies and non-trekers among us, this bit of star trek culture is supposedly the big rule for the federation in interacting with cultures less developed then themselves. basically, it states don't reveal your "superior" technology to "inferior" cultures lest you mess with their "natural" development. incorrectly applied to the native americans and the conquistadors, and acurate real-life example would be the japanese around world war 2.
first we look at the industrial revolution
here and
here. very generally speaking, the industrial is considered to have taken about 200 years, which is sufficient generalization for my purpose. now, prior to the late 1800s, the japanese were still a feudal agrarian society, which is about the default assumption of time period for many oriental settings in fantasy. from about 1867-1912, a space of 45 years,
they duplicated the entire 200 years worth of industrial revolution, catching up with everyone else with a vengeance.
this has led to what is called, in prime directive terms, an "impacted culture". instead of learning and developing unique takes on technology on their own, they just cherry-picked whatever technological, social, and political reforms caught their eyes. in fact they sent out many "diplomats" (ie:scientists) to tour all manner of facilities in order to copy foreign tech. speaking from my own personal experience, when i lived in japan only 15 years ago, most of the japanese i have personally spoken to had never heard of or seen electric popcorn makers, or can openers where you turn/rotate/spin the handle to open a can, let alone electric can openers. they have sat-nav in their cars, and phones the size of lighters, but the houses are made from 3rd grade lumber, cheap concrete, and tin. medical tech lags by about 10 years or more, depending on area. (seriously, despite all the anime and manga to the contrary, you do NOT want to end up in a japanese clinic or hospital when overseas.) they have some of the best game systems, and hovercrafts for bumper cars in game centers, but there are still areas of japan in which people have never met a foreigner. \
there are numerous other tribe examples out there. the native tribes living in japan before the arrival of the japanese qualify too.
anyhow, back to the fantasy discussion. in fantasy, magic = tech. at some point in time there would have been a magiological revolution by some culture or cultures. in fact, most fantasy games have epic or artifact items as left overs from just such a culture.
from an archeological point of view, we live in a graveyard of dead and lost cultures today, so the whole dungeon here, there, and everywhere is not as bad an assumption as one might think. (though rarely is usable tech recovered, even if evidence of such tech is found, let alone tech more advanced than ours today... yes, there are a few, but anyway... so the whole magic item thing is a bit over the top.)
given d&d's dependence on the vancian system of magic, and the subsequent reliance on material components, and given even the unlikely population and class and level demographics listed in the dmg, you would literally need slaughter farms of various magical beasts in order to supply even a modest country's need for magical components. forgotten realms and eberron sort of approached this, but failed to execute it really.
so your two basic scenarios of advanced magical cultures involve:
1) magiology slowly developing over time, which would imply trade, and a general availability of tech with said availability and advanced forms being top heavy towards a government and military bias. certain nations might have specializations due to available local resources, and if one or more can dominate particular resources, they can become superpowers. access to other planes might allow disproportional resource access compared to size, population, and local resources of a given country. unless planar locals object to said mining; which is a whole 'nother story.
2) impacted development, which involves cherry picking from more advanced resources, not all of which may be fully understood. this results in swift development, but a chimeric patchwork of advanced and primitive and all in-between. mining ancient magiological tech or copying / trading with a more advanced group or similar could explain this.
there may be other methods of development, but these are the two main ones we can draw from experience of in our own world. some things to consider is the sort of tech one could make without fire, such as in an underwater environment, or in outer space. each has possible exceptions: deep sea thermal vents (dangerous and poisonous), and solar lenses to create heat.
any discussion of costs and resources should really be considered against one of two said backdrops. d&d is notoriously silent on the more detailed aspects of economy and commerce necessary to support the supposedly widespread availability of magical items implied by the gp limit of towns of various sizes. a few sketches are set forth as guidelines, and the rest, without much in the way of background is dumped in the dm's lap. as a result, it is seldom developed, and thus we have the rules we have with all the nonsensical results we are debating here.
ps: just as an interesting side note, most fantasy settings are explicitly post-apocalyptic. greyhawk has the twin cataclysms, plus numerous other local catastrophes. forgotten realms has its share, plus the recent one that converted FR from 3rd to 4th. dark sun is a prime example as well, as is hollow earth, savage coast, and most others. the time frame of said apocalypse varies from setting to setting, but they pretty much all have them.
pps: some have wondered why there is no mass combat rules in 3rd, when every version previous has had them?
here is your answer. and the mass combat rules you are looking for.
