|Leopold Von Ranke,|
the original GURPS afficionado
History is all about asking questions about the past, then interrogating the available evidence for answers. At its core it is a matter of finding the right questions. If you are GMing a world, whether it is from our own history or one built on historical analogs, questions naturally arise on their own: how does land ownership work? who controls nearby natural resources? how much salt can a salt mine produce annually? how much how much is 120 tons of salt worth? what exactly did the grand council do on a daily basis?
Each of these questions may have different answers depending on the period you are drawing from or playing in. Answering one question from this list could take five minutes or it could take two hours or more (and if you really want to be thorough about it, your probably not spending enough time if you find the answer in just five minutes). I've even gone days or weeks unable to answer what seems like a relatively simple question. It can be a matter of getting your hands on the right book or it simply being a question that historians haven't answered directly. If you are fortunate enough to be able to read the primary source material in its original language, then that might help you, but even then it can be difficult finding such documents. And if your setting covers a vast selection of cultures, it is unlikely you will be able to read primary sources from more than one or two of them without a translation.
I find when I am running a campaign, questions like this regularly come up. Because I enjoy it, I often answer all of them or as many as I can (or at least try to find some approximation that works). Still sometimes I have to move on. And for some campaigns, it really isn't worth the energy when I can just invent a detail myself. The point is, these take time, so you have to weigh any decision to answer these sort of questions against the fact that this time could be spent on building other campaign details.
One issue GMs will frequently encounter is the questions that arise out of the need to run a game, are often not the questions historians ask when they write papers and books. This is why you will sometimes find a historical RPG supplement that doesn't seem to provide any real information on the nitty gritty of managing a day-to-day game (because most of the secondary sources the writers read probably addressed more general questions and only occasionally answered specific ones a GM might have). There are exceptions to this. If you learn the historiography of a particular topic, you can eventually find many answers to those difficult questions. There are also plenty of gamers and history enthusiasts online who have aggregated those answers.
I notice that when I do invent details rather than answer the above questions, these sometimes give more color and coolness to the setting. It can just free me up more to make bold declarations like "There is an Ice City here, ruled by a mad king and filled with immortal inhabitants who don't die but whose bodies wither with time". I like that, so I give myself license to make things whole cloth where it feels like it would add something. But I also like having my campaign grounded in something that to me feels real, so I still spend a bit of time doing research.
However my point is, I only do this because I enjoy it. Unless my players are all history nerds, it really isn't that important. They want consistency but they don't expect historical realism. This has been true of most groups I've gamed with. Unless the campaign is set in a specific period of history, and unless the tone of the campaign suggests historical realism, I find most gamers are okay with things being a bit fast and loose.
|"Are you not entertained?"|
So if you have a setting that is vaguely Roman, you can go as deep as you want with real world Roman history, but you don't have to. There is nothing stopping you from taking a Roman veneer and using other elements for the actual social structures (either of your own invention or maybe even taken from movies and books). I like Rome, but I am not going to care if a GM runs a world with a Roman-like empire but it doesn't have the same social orders or the patronage system. If the GM decides it is run by a council of wizards and they enforce their rule through a network of undead knights, well that seems like a blast to me.
Why this matters to me is because I occasionally see folks begin resenting history because of calls for historical realism where they don't necessarily feel it is important (or where it feels like there is pressure for them to demonstrate advanced historical knowledge). I think it is possible to be so enthusiastic about real world history that you can stomp the joy of it from others. So I'd rather it be seen as a positive tool GMs can draw on as needed, rather than a requirement to gain a sense of legitimacy as a GM. I like history, and I want others to like history, so I would encourage my fellow history enthusiasts who also game, to not use history as a weapon in conversation or to inflate one's own ego. Instead share it when it is helpful and encourage enthusiasm in others.
I've done this myself. When the film Gladiator came out, I was excited because I had been reading a lot about Marcus Aurelius and writing papers on the Meditations. But I pretty much ruined the movie experience for anyone who happened to see it with me. It didn't fill them with a sudden interest in history, it just made them think I was a smart ass who clouded the fun of going to the movies by criticizing every little detail. After that I made a conscious effort to be more laid back and positive about my love of history.
Historical Realism is a wonderful tool to have at your disposal. It also can form a strong foundation for a particular style of GMing that gives a world a very powerful sense of life. But it isn't a requirement. When trends become requirements, people react against them. Personally, I am more comfortable running games that lean a lot on actual history. But that doesn't make me better than the GM who just slams down a bunch of orc vikings and halfling pirates in a strange anachronistic hodgepodge. In fact, that GM is probably a little more creative than I am. I may have read more books about things like the Nika Riots, Imperial Chinese Bureaucracy but he or she probably read way more fiction, comics and fantasy novels than I have (which are great sources of inspiration for gaming). And I also find that the more I lighten up and allow for unusual elements to spread in my campaign (often at the expense of Historical Realism) the more playable the world becomes.