When we talk about map literacy, we mean the ability to read a map. We can blithely talk about how map reading has changed over the centuries while failing to interrogate whether what we mean by map reading has changed as well. It’s presentism to assume that people in the past did things the same way as they do today. In a useful essay called “Maps, Travel and Exploration in the Middle Ages: Some Reflection About Anachronism,” French academic Patrick Gautier Dalché explores how medieval audiences interpreted mappae mundi and marine charts. Even a mappa mundi, he argues, has a practical function. Spoiler: it’s not how you or I would use them.
It also occurs to me that Dalché’s paper is a must-read for writers of fantasy novels (and fantasy map makers), who might also fall into the trap of assuming that their characters would use their maps the same way as a modern map reader would.