"Things You Wouldn't Know If We Didn't Blog Intermittently."
In the bottom right it says /u/yetkinler ... that's a reddit username. Go to reddit and leave them a message if you want more info.
Thanks for that suggestion. I was able to trace the map credit to https://www.reddit.com/r/empirepowers/which is a gaming reddit. Not sure if they use historic or fantasy maps, tho. Clearly this map is reality-based, but ?precision.
At least they've got the geography of the Netherlands right. It's all too common to encounter these maps with the modern polders already in place.
You might be interested in the video showing 1,000 years of Europe in (just over) 3 minutes: https://youtu.be/Iha3OS8ShYs
Although Mark Twain's narrator in A Connecticut Yankee In King Arthur's Court was speaking of Britain and a much earlier time his reference to how "people had to sleep with their knees pulled up because they couldn't stretch out without a passport" seems just as apt for Europe in 1500.