I came across this post > https://i.pinimg.com/originals/61/51/24/615124ce2c5e1616153bbd48b54691c7.jpg > which is a guy debunking things that happen in fantasy novels but aren't actually historically accurate. It's not to do with dragons, or racism/ sexism, it's more like 'why aren't characters teeth rotting out', 'why are characters drinking ale all year round' and 'where is the merchant class' etc. and I found it really interesting and wanted to know more.
I'm really into history and anthropology, and am trying to write a novel that is historically realistic - think Game of Thrones fantasy (historical fantasy and realism), Vikings, and Black Sails, rather than LoTR fantasy. I was wondering if there is anything else that a lot of fantasy books do that just aren't realistic/ accurate to history, or if there's historical misconceptions people make about the medieval period (in Europe/ England) and how people lived. Or else, stuff that you would want fantasy writers to know about getting medieval history right.
The debunking post gets several basic things wrong (like their surprise at fantasy people wearing wool, drinking ale through the winter and apparently also at fantasy people having domesticated wheat), which illustrates my problem with these sorts of lists. Working off a list of "errors" is considerably less useful than reading the relevant literature as, somewhat ironically, ASOIAF demonstrates with admirable error.
Medieval history is also a considerable field, and information about 14th century England is not necessarily relevant for 10th century German or 13th century Bohemia, so "misconceptions" may be solely about a single period or place rather than the medieval world as a whole. What period and rough geographic location do you want to use, and what are the themes you want to explore in your story?
You may find our previous AMA over on r/fantasy interesting.