Well, the graticule (grid) is a bit problematic. Being square like that implies that the map is either, large scale ("zoomed in") and centred on the equator, or it's in Plate Carree projection, in which case the features on the map would be distorted, unless it's a large scale map centred on the equator. Based on the terrains though, I'd say it's at a temperate to subtropical latitude.

There are other coordinate systems besides latitude and longitude that you can present with a graticule which might be scare in other situations, but they wouldn't really be appropriate for fantasy a map like this. In fact, for a high fantasy map like this, even a lat-lon graticule is a bit anachronistic feeling.