ThePersian, I also have a degree in military history (I'm majoring in this, and I'm also working on my Ph.D in this) and a seperate degree on Mediterrainian civilizations and what-not. So, ya, that and good sources, and a little practice with Civ III (on taking out everyone -- military history related), would make me a lugatimate historian who (obviously) knows his stuff, unlike Ghafhi. Now, I'm by no means trying to bragg (I HATE bragging), but, if you need to know anything historically related, I'm the guy to see. Not to say that there arn't other people out there who are as good as/better than me (Belcarius seems to be an example of this -- he knows his stuff).
Perhaps a benifit of this is that you gain an edge when playing Civ. For example, knowing how the ancients built their civilizations gives you handy knowledge as to how to build yours. And, espically related to this thread, it gives you the necessary knowledge to know which civs in Civ III should be used in Civ IV.
Most of the European civs are what you can call real civilizations, except the Celts. Though they are the precedents of the French and English, and perhaps a little of the Spanish, they weren't an actual civilization, just a collection of tribes. Same with the Iroquois. Granted, I like the fact that they're in Civ, but as a civilization, they just don't work, again because they are tribal-based. Since they are tribal-baesed, that generally means that there is no central government, no standing army, no set form of currency (this becomes a necessary factor in the later ages), etc. Now, when you look at the Romans, yes, they were based on a family-like thing, where each family was it's own sort of faction (this is true, not out of Rome: Total War), but they were all united under one central government, and eventually these sub-factions dissapered all-together.
Some civilizations are wrongly critizied in this manner, though. The Zulu, for example, are generally thought of as a purely tribal soceity that had none of the characteristicts of civilization. BUT, the Zulu were actually a true African civilization. They had a central government, centered at Great Zimbabwe. They had a standing army, public agencys -- basically everything that is used to define a people as a civilization. Though I'm only directly using a central government and a standing army to justify which is a civilization and which is not, there are many more ways to define this. I'm only using these examples just for the sake of simplicity (for me). The only reason why the Zulu are mistook for "barbarians" is that this central government disapeared circa the Middle Ages. For what reasons, nobody is actually sure. But whatever the case, they degenerated into a tribal soceity (I'm in no means calling a tribal society uncivilized or bad, just not what you'd could call a nation).
Of course, the Americans can be attacked for being in Civ, simply because they are only 230 years old, and were once a former colony of Britian. Because they are what some would say "off-shoots" of the British, generally people feel that the Americans shouldn't be in historcal games such as Civ. However, the reason they are in the game is because A) Americans buy Civ and B) the Americans have been extremely influencial in the past 100 years. And thus they are included in game. And then this could leed to why the British and French are in here since they are from the Celts, but they are in the game for the same reasons as the Americans: they've been influencial in world history (and Civ sells in those countries).
I don't want to go into anymore detail in one post, since this is already getting long (sorry), but if you feel necessary to question anything in this, please do so. But, none the less, I feel that the Africans are represented in Civ fairly.